As voters around the country prepare to pick their presidential candidates in some 20 state primaries on “Tsunami Tuesday” next week, Californians will play a crucial role in shaping the outcome of the winner for both parties.

Since moving its presidential primary to Feb. 5, from late March in previous election cycles, both Democratic and Republican candidates will need to focus a tremendous amount of attention and resources on the Golden State. Although the state has always been influential in the general election, the earlier primary allows the state to be a key player in the nomination process.

With approximately 20 percent of all the country’s delegates to be distributed to the respective winners, California has become a bellwether for both parties, shifting some of the power away from smaller states that typically dominated early primaries, like Iowa and New Hampshire.

“California is more important because it’s an independent test of viability of these candidates,” said David Tabb, a political science professor at SF State.

Exactly who will capture the coveted state, however, remains to be seen — for both the GOP and Democrats.

With the Florida primaries now settled, the GOP has a clear front-runner, and the Democratic field has been narrowed down to two, with several candidates leaving the race.

The Republican nomination in particular may be decided with a win in California. Two heavy-weight candidates — Sen. John McCain of Arizona and former Massachusetts Gov. Mitt Romney — will be jockeying for votes here in hopes of capturing enough momentum and delegates for a decisive national lead.

A key factor for Republicans, Tabb said, was McCain’s pivotal victory in Florida, earning him all 57 delegates from the state. The win for McCain established the once-faltering senator as the clear front-runner heading into the Feb. 5 primaries. Romney, though, is far from dead, and a strong showing in California could easily thrust him back into front-runner status.

The Republican primary in California, like Florida’s, is closed to voters not registered with the party, making the win in the sunshine state all the more relevant for McCain. With strong support from independent voters, political pundits and analysts had speculated that with the independent vote shut out, Romney would gain a clear advantage over McCain. But the Arizona senator’s ability to gain the vote of party loyalists gives him an edge in California and the rest of the country heading into the Feb. 5 primaries.

“I think California solidifies the nomination for the GOP,” Tabb said.

The win by McCain, with Romney in a close second, effectively killed any hopes for at least one other GOP candidate, former New York City Mayor Rudy Giuliani, who officially dropped out of the race on Wednesday and announced his support for McCain. The chances for former Arkansas Gov. Mike Huckabee, who will likely withdraw from the race within the next week, were also severely diminished.

Giuliani, a moderate, staked virtually all of his hopes in less conservative states like Florida and California, but his resounding loss to McCain and Romney dashed any hopes of a comeback. Huckabee’s distant fourth-place finish indicates the lessening influence of the evangelical vote — his core base — and may suggest moderates and GOP loyalists could choose a more mainstream candidate in this election.

One unpredictable demographic for both parties, Tabb said, is the absentee voters, who make up 40 percent of all voters in California.

For the Democratic front-runners, different challenges lie ahead in securing a victory in the heavily blue state.

One result of the Florida primary for Democrats could play a factor for New York Sen. Hilary Clinton and Illinois Sen. Barack Obama — the elimination of former North Carolina Sen. John Edwards, who failed to win any of the five primaries. His departure effectively narrows the Democratic field to two candidates, assuring a historic nomination of either a woman or a black man for the presidency for the first time in American politics. Edwards typically came in third place in the primaries, so the votes he leaves could be crucial for either remaining candidate. Edwards has at times tried to align his message with that of Obama’s, which was seen as a way to draw votes away from Clinton. An endorsement could go a long way, too, though he has yet to back either candidate.

Clinton has a roughly 12 percent lead in California over Obama, according to several polls. But beyond the volatile polls, Clinton holds several other advantages. Her largely symbolic win in Florida gives her momentum, but no delegates were awarded to either candidate because the state ignored the Democratic National Committee’s warnings to not move its primary to January.

Hispanic voters, considered crucial to any race in California, seem to be mobilizing in Clinton’s favor, particularly in densely populated Southern California, according to polling data. Such support from the Latino constituency, Tabb said, is consistent with her support from blue-collar Democrats, a strong voting bloc around Los Angeles and its suburbs. L.A. Mayor Antonio Villaraigosa endorsed Clinton, which is seen as a major benefit.

“The largest support group for Clinton seems to be the Hispanic vote,” Tabb said. “We’ll see if Obama can tap into that vote. Where Obama hasn’t been able to break into is the working-class vote.”

But Obama is far from out of the race, with strong support among an increasingly powerful voting group that is expected to come out in full force — young Democrats, many college-aged and under 30 years old. While Latinos could make up as much as 25 percent of the vote, the younger voters may have an equally important impact in choosing the Democratic candidate, said Graeme Boushey, a political science professor at SF State who specializes in California politics.

About 2.6 million voters in California fall in the 18-to-29 year old range, which is about 16.5 percent of registered voters in the state, according to the Associated Press.

Obama also seems to have strong support in Northern California, where much of the upper class white liberals around the Bay Area have rallied around the Illinois senator. As one of the first black candidates to have a serious shot at the White House, he is also expected to draw large support from African-American communities throughout the state. Obama is actively pursuing the Latino vote, and a key endorsement from Massachusetts. Sen. Ted Kennedy could go a long way to woo those votes away from Clinton, who purportedly has a 3-to-1 advantage among the state’s Latino population.

Southern California will play a key role for both Clinton and Obama, but “[Obama has] got to carry Northern California. If he doesn’t, he’s got no chance,” Tabb said

Although the Democratic winner of California will have a major advantage, the runner-up should still be able to stay competitive, unlike the almost winner-take-all situation GOP candidates may find themselves in, both Tabb and Boushey said.

The Democratic primary is open, meaning more liberal independent voters could join the fray. Among that voting bloc, Obama draws stronger support, with roughly 62 percent finding him favorable nationwide, compared with 47 percent for Clinton, according to the Pew Research Center.