国际英语新闻:Republican Primaries in Alabama, Mississippi Too Close to Call

The three top Republican presidential candidates are locked in a tight race, as results trickle in following primaries Tuesday in two southern U.S. states.

Exit polls and early results in Alabama and Mississippi show Mitt Romney, Rick Santorum and Newt Gingrich are in races too close to call. 

The results of the races in those two predominantly conservative states are important to each of the candidates. 

Romney is hoping for victories to propel him forward and prove he can win over very conservative and evangelical Christian Republicans, who have been drawn to his main rival, former U.S. senator Santorum.

Santorum wants to knock Gingrich out of the race to stand as the sole conservative challenger to Romney.

Gingrich, a former U.S. House speaker, has focused his efforts on the southern vote and is hoping victory on Tuesday will make him the comeback favorite for the nomination.  Otherwise, he could face increased calls to drop out.

Romney, a former Massachusetts governor, is far ahead of the others in the delegate count, winning nearly 40 percent of the 1,144 needed to secure the party's nomination. 

A new Washington Post-ABC News poll shows he leads U.S. President Barack Obama in a hypothetical election match-up (49 to 47 percent), while Santorum would be in a competitive race, three points behind (46 to 49 percent) Mr. Obama, if the election were held now.

The other Republican candidate, U.S. Representative Ron Paul, has not won a nominating contest.  He has single digit support in Alabama and Mississippi.

The Pacific island state of Hawaii and the U.S. territory of American Samoa are holding caucus elections on Tuesday. 

The Republican Party will formally nominate its presidential candidate at its convention in Tampa, Florida, in late August.  The nominee will face Mr. Obama, a Democrat, in the November election.