Preview: U.S. presidential hopefuls face crucial tests in S.C., Nevada

Backgrounder: Key players in S.C., Nevada presidential nomination races

Backgrounder: Nevada caucuses in U.S. presidential nomination race

Special Report: U.S. presidential election 2008

    WASHINGTON, Jan. 19 (Xinhua) -- Voters headed to the polls and caucus sites Saturday in presidential nomination races in South Carolina and Nevada.

    The contests could propel one candidate from each major party to front-runner status in this year's wide-open presidential races.

    PATH TO REPUBLICAN NOMINATION

    A win in the South Carolina Republican primary could give one of the candidates a hand up in a race that has so far produced three different winners in three major contests.

    Democrats will have their primary in the state a week later.

    Historically, the path to the Republican nomination has gone through South Carolina, which relishes its role of being the political gateway to the South.

    Recent polling in South Carolina has Sen. John McCain as the front-runner in the state.

    An American Research Group poll conducted on Jan. 15-16 had McCain leading at 33 percent, followed by Mike Huckabee, the former Arkansas governor, at 23 percent.

    Mitt Romney, the former Massachusetts governor, was at 20 percent, and former Sen. Fred Thompson was at 13 percent, the poll found. All other candidates were in single digits. The poll's margin of error was plus or minus 4 percentage points.

    No GOP candidate has gone on to win his party's nomination without winning South Carolina since Ronald Reagan won there in 1980, but, with the race so volatile, that may not hold true this year.

    DEMOCRATS BATTLE FOR MOMENTUM

    Democrats will shift their focus west to their caucuses in Nevada. The race there will be very different from the earlier contests back East.

    A Las Vegas Review-Journal poll conducted by Mason-Dixon suggests that the Nevada caucuses will come down to a race between Sen. Hillary Clinton, the winner of the New Hampshire primary, and Sen. Barack Obama, the winner of the Iowa caucuses.

    The poll, conducted on Jan. 14-16, had Clinton leading Obama 41percent to 32 percent.

    Former Sen. John Edwards came in third at 14 percent. All other candidates were in single digits.

    In short, the Democratic candidates are battling in Nevada for momentum going into "Super Tuesday" on Feb. 5, when 22 states hold primary elections.

    Nevada will also be the first test of the Democratic candidates' support among Hispanics.

    ROMNEY HAS ADVANTAGE IN NEVADA REPUBLICAN CAUCUSES

    Nevada Republicans are also expected to hold caucuses Saturday, and Romney is campaigning hard there as other Republican candidates have kept their focus on South Carolina.

    Even though the Republican party cut in half the number of delegates the state party can send to the national convention as punishment for moving its caucuses to Saturday, Nevada has more delegates at stake than South Carolina.

    In a presidential race that is increasingly coming down to who has the most delegates, a win could help Romney, who is expected to benefit from Nevada's large Mormon population.