Three-term Sen. Barbara Boxer is getting help of the highest level as the Democrat starts what could be a tough re-election campaign.

President Obama will travel to California next month to headline a joint fundraising event for Boxer's campaign and the Democratic National Committee.

Boxer is running roughly even with her potential Republican challengers, according to the latest Field Poll, which tested Boxer against three GOP candidates.

The results:

Against Tom Campbell, it was Campbell 44 percent, Boxer 43 percent.

Against Carly Fiorina, it was Boxer 45 percent, Fiorina 44 percent.

Against Chuck DeVore, it was Boxer 45 percent, DeVore 41 percent.

Margin of error: 3.7 points

CQ Politics currently rates the race Likely Democratic. Check back to see whether that changes. And you can follow all the 2010 Senate races with our election map.

The battle lines are being drawn in the Republican primary for California's 11th district seat, with a number of the GOP candidates lining up notable recent endorsements.

Elizabeth Emken (R), former vice president of the group Autism Speaks, snagged the endorsement of Manteca, Calif. teacher and former rival Jeff Takada (R), who dropped out of the race last week. Takada said that of the remaining field, he believed Emken is "best positioned to defeat [incumbent Democratic Rep. Jerry] McNerney in 2010."

The decision by Takada and businessman Robert Beadles to end their bids before last Friday's filing deadline narrowed the field to four contenders for the Republican nomination.

Former U.S. marshal for northern California Tony Amador (R) is one of those four. He received the endorsement Tuesday of Rep. Tom McClintock (R-Calif.), one of the California delegation's most outspoken conservatives. Amador, McClintock said, "will stand firm and oppose a government takeover of our healthcare system. I cannot think of anyone else who has the integrity and toughness to be the next Congressman for the 11th District."

Another poll shows Sen. Barbara Boxer (D-Calif.) in a tight race for re-election in 2010, leading three prospective GOP challengers by single digits.

A Rasmussen Reports poll of likely California voters found that Boxer led former Rep. Tom Campbell (R-Calif.) by just two percent -- 43 to 41 percent.

Boxer led both former Hewlett Packard CEO Carly Fiorina (R) and state Assemblyman Chuck DeVore (R) by 6 percent, 46 to 40 percent.

A conservative advocacy group that was involved in the Prop 8 ballot initiative campaign that banned gay marriage in the state is revisiting the issue, this time in the context of the Senate race.

National Organization for Marriage launched a $275,000 statewide ad campaign Monday that critiques Tom Campbell's (R) support for gay marriage, dubbing the former congressman and Sen. Barbara Boxer (D-Calif.) as "two peas" from the "same liberal pod."

The ad also likens Campbell's position on taxes to Boxer's and asks, "is he really much different?"

It's candidate filing deadline day in California, Maine and Montana. Idaho and Iowa have their turn at the end of the week. And in between, some fun in Colorado.

On Tuesday, Colorado's political parties hold precinct caucuses. Yes, it's the lowest level of party organization, scattered and hard to follow, but it'll be worth monitoring because there's been a lot of grumbling among Democrats there about being dictated to by Washington. The caucuses will be a chance for those who feel that way to find out just how many kindred spirits are in their own back yard -- or the reverse, how many of their fellow Democrats locally want to see appointed Sen. Michael Bennet win election, as President Obama wants.

Here's the cheat sheet to get ready for caucus day:

Former Rep. Tom Campbell (R-Calif.) is within the margin of error in a hypothetical match-up with Sen. Barbara Boxer (D-Calif.) in a new Research 2000 poll conducted for the liberal blog Daily Kos.

Boxer, the three-term incumbent, leads Campbell 47 percent to 43 percent among likely California voters with 10 percent undecided. But Campbell tops Boxer among independents, an increasingly significant chunk of the state's registered voters, 45 percent to 43 percent. The poll, conducted March 8-10, has a margin of error of 4 percentage points.

Nor does Boxer have commanding lead over the two other potential Republican nominees. She tops former Hewlett-Packard CEO Carly Fiorina 49 percent to 40 percent with 11 percent undecided. And she leads GOP state Assemblyman Chuck DeVore 49 percent to 39 percent with 12 percent undecided.

Worth a look this morning: The Los Angeles Times prepares for this weekend's state Republican convention by examining how Insurance Commissioner Steve Poizner came to be trailing Meg Whitman for the GOP gubernatorial nomination.

Poizner has mostly been sitting on a $19-million campaign war chest while Whitman has outspent him dramatically in an effort to put him away, the newspaper reports.

"If you're a legislator or a donor or a grass-roots activist and you see your candidate slipping further and further behind in the polls," says former Republican operative Dan Schnur,"you may know that there is a strategy . . . but it still makes you nervous."

By letting Whitman get so far ahead, "He's definitely dug quite a hole for himself," Schnur tells the Times.

CQ Politics rates the California general election Leans Democratic.

To follow all the 2010 races for governor, check out our election map.

Former Rep. Tom Campbell's (R-Calif.) Senate campaign is heralding its latest fundraising benchmark: $1 million raised since entering the race in mid-January.

The breakdown, according to the campaign, is $767,000 for the primary and $234,000 for the general election.

The Campbell campaign announced in mid-February that it had raised $700,000 in its first month in the Senate contest after shifting over from the gubernatorial race, which means it saw a big drop-off in the second month, to approximately $300,000.

However, the figures still put him on a competitive fundraising pace with GOP primary rival Carly Fiorina, the former CEO of Hewlett-Packard, who raised just over $1 million since beginning her fundraising in September, according to her year-end report. Fiorina also contributed $2.5 million of her own money to the campaign, however, and ended 2009 with $2.6 million in the bank.

California's three Republican Senate candidates got to throw their punches live, rather than via the press or other intermediaries, in a radio debate Friday that underscored how acrimonious the primary race is becoming.

Former Rep. Tom Campbell, the current frontrunner, was subject to most of the jabs from rivals Carly Fiorina, the former CEO of Hewlett-Packard, and state Assemblyman Chuck DeVore, during the debate on Sacramento, Calif.'s conservative KTKZ station, all over his stance on Middle East policy and prior associations with radical Muslim activists.

The topic has transfixed the GOP contest in recent weeks, and prompted Campbell to call for the foreign policy debate.

In their discussion, Campbell denied that he was anti-Israel, a charge lobbed at him by Fiorina, but admitted that he should have "done a better job finding out" about some of his past associations, including the background of an extremist who donated to his campaign in 2000. He also hit back against Fiorina's assertion that he voted to cut aide to Israel, saying he opposed adding $50 million more in aide to Israel because it would be subtracted from Africa's aide.

Here's the latest tally of Democratic House members who have are giving up some or all of their donations from Rep. Charles B. Rangel (D-N.Y.), the 20-term Ways and Means Committee chairman who was recently admonished by the House Ethics Committee:

• Bill Foster (Ill.)
• Gabrielle Giffords (Ariz.)
• Jim Himes (Conn.)
• Ann Kirkpatrick (Ariz.)
• Jerry McNerney (Calif.)
• Walt Minnick (Idaho.)
• Carol Shea-Porter (N.H.)
• Dina Titus (D-Nev.)
• Niki Tsongas (Mass.)

All nine are freshmen or sophomores and all but Tsongas are in races that CQ-Roll Call rates as competitive.

As promised, Attorney General Jerry Brown gave his Republican rivals a break from their months of shadow-boxing.

Brown today declared his candidacy for the Democratic gubernatorial nomination.

You can watch it here:

So far, it's looking as though today in the political world is going to be all about endings.

If the candidates motivated by "tea party" frustration don't do well in the Texas primaries, tonight will bring a lot of cable TV chatter about how broad-based the "tea party" is and whether the movement was overestimated. And if any of those candidates win, the chatter will be about the end of business as usual in the Republican Party.

In California, today's going to bring the end of a phase in the governor's race that's been entertaining to watch from afar.

Democrat Jerry Brown has been vexing the Republicans who want to run against him by taking his time about running at all.

It can be amusing to watch grownups ball their fists and stomp their feet and complain about somebody else being juvenile. You've seen that for months in New York, where Republican gubernatorial candidate Rick Lazio is tired of waiting for Democrat Andrew Cuomo to start his campaign, and Californians have been seeing it from the rivals who'd much rather target their attacks on Brown than on each other.

As the Los Angeles Times reports, today's the day Brown puts them out of their misery.

This is the end of the line for the playing-possum phase of the race in California and end of the line for the initial speculation about what the "tea party" movement's all about. If nothing else happens, that's still a pretty full political Tuesday.

California Republicans have figured out that instead of pummelling each other in their bruising battle of the billionaires, they'd rather go after a Democrat.

So, Republicans have started demanding that Attorney General Jerry Brown, who's widely expected to be the Democratic nominee, do some campaigning, reports the San Franciso Chronicle.

Brown has an exploratory committee and has until March 12 to make his candidacy for governor official.

California Assembly Speaker Karen Bass (D) has quickly cemented her place as retiring Rep. Diane Watson's (D-Calif.) heir apparent.

Bass, who confirmed last week that she will run for the Los Angeles-based 33rd district seat, already has the backing of Watson, who promptly endorsed her.

And so far this week, Bass has sewn up the backing of abortion rights group EMILY's List as well as senior Sen. Dianne Feinstein (D-Calif.).

Worth a read this morning: A look at how California candidate Tom Campbell deals with the differences between running for governor and running for senator.

As a candidate for governor, this San Jose Mercury News story explains, Campbell proposed a one-year, 32-cents-per-gallon increase in the state gasoline tax to help bridge the deficit.

But now he's running for the Republican nomination for senator, not governor. "If his opponents are successful telling the Tom Campbell-as-tax-hiker story, he will have a very heavy lift on his hands," Chip Hanlon of RedCounty.com, a network of Republican blogs, tells the newspaper.

Said Campbell: "I think most people are taking that as a sense of pragmatism."