12 p.m. SACRAMENTO -- California Gov. Arnold Schwarzenegger Thursday moved the presidential primary of the nation's most populous state to February, shaking up the 2008 race and making a one-day, mega-primary increasingly likely.

''Now California is important again in presidential nominating politics ... and we will get the respect that California deserves,'' Schwarzenegger said during a bill-signing ceremony.

California has not played a prominent role in a presidential primary since 1972, when George McGovern beat Hubert Humphrey for the Democratic nomination. Schwarzenegger is hoping that by moving the presidential primary from June to Feb. 5, the state will again play a significant role.

California is one of as many as two dozen states that have selected Feb. 5 - or are considering that date - for one or both of their Democratic or Republican primaries or caucuses. Other states that have already set that date for their primary are Alabama, Arkansas, Delaware, Idaho (Democrats only), Missouri, and Utah. Also, New Mexico Democrats have set their presidential caucus for Feb. 5, and the West Virginia GOP plans to hold its state convention, where selects presidential candidates, on that date.

Among the 15 other states considering moving their contests to Feb. 5 are Florida, Illinois, Michigan, New Jersey, New York and Texas.

The prospect of an early primary has already prompted presidential candidates from both parties to add California to their itineraries, along with the handful voting states that lead off the nomination contests in January: Iowa, New Hampshire, South Carolina and Nevada.

Democratic political consultant Jenny Backus said the rush of states to move forward to Feb. 5 only increases the importance for candidates to get a win in the early nominating states in January.

''To go to California, you are going to need a huge head of steam,'' she said. ''California moving up actually makes more attention go on the first lap. Even if you have all the money in the world, it will be hard to catch up to somebody who has racked up some victories in the first states.''

She said the move is not good for democracy because it compacts a primary election that helps weed out weaker candidates and energize voters.

''It's very disappointing to see all these states to try to front-load the process,'' Backus said. ''I think the party and the process got stronger in 2004 by trying to stretch out the calendar.''

Republican candidates John McCain and Rudy Giuliani have appeared at Schwarzenegger's side during campaign trips to California.

''Before the election, it's already accomplished what we set out to do: The candidates for president are already in California. They're already talking with us. Before they would just come, raise money and leave,'' said Democratic state Sen. Ron Calderon, a sponsor of the measure.

Many Republicans, particularly in the state Assembly, opposed moving up the primary, saying it would cost counties too much money to hold an extra election. But as he signed the bill, Schwarzenegger pledged to reimburse counties for the cost, which local officials estimate between $60 million and $90 million.

Associated Press writer Nedra Pickler in Washington contributed to this report.