With a big win in the Illinois primary Tuesday, Republican presidential hopeful Mitt Romney built momentum on Wednesday to be the GOP challenger to Barack Obama in November, winning the key endorsement of former Gov. Jeb Bush of Florida -- and drawing fire from the Democrats.

Romney won Illinois with 47 percent, while Rick Santorum was in second with 35 percent. Ron Paul took third with 9 percent, followed by Newt Gingrich with 8 percent.

With Illinois having its say on Tuesday, Louisiana, which will have 46 delegates at the GOP convention in Tampa, is next in line with a primary on Saturday -- and the Republican presidential candidates are starting to focus on it.

This primary is shaping up to be the most important GOP presidential battle in the Pelican State since 1996, when Pat Buchanan effectively set himself up as the conservative alternative to Bob Dole by crushing Phil Gramm in the Louisiana caucus, which was actually held before Iowa in that election cycle.

Marco Rubio drew national attention for his win in the 2010 U.S. Senate race when he drove the heavily favored Charlie Crist out of the Republican Party to run with no party affiliation and started generating buzz that he'd wind up on a Republican presidential ticket in 2012 or down the road.

That buzz grew louder this week as Rubio announced that the publication date of his new book, "An American Son," will be moved up to June 19 -- leading to increased speculation that he could wind up on the GOP ticket in the vice presidential spot.

While Republicans have little hopes of stealing Barack Obamas home state in November, with 69 delegates, the Land of Lincoln will hold a prominent spot at the Republican convention in Tampa. As Republicans across the state hit the polls on Tuesday to vote in the primary, a poll released on Monday finds Mitt Romney has a large lead in Illinois.

While he has yet to win a primary and his only caucus win was in the Virgin Islands -- where Mitt Romney got more delegates -- U.S. Rep. Ron Paul of Texas continues his bid for the Republican presidential nomination, focusing on the Illinois primary on Tuesday as he looks to continue his campaign all the way to the Republicans' convention in Tampa in August.

While Democrat incumbent President Barack Obama is an overwhelming favorite to carry his home state in November, Illinois will have a large role in Tampa -- and 69 delegates to boot.

Looking back at American history, some of the most dramatic presidential elections have resulted from former officeholders running as third party candidates -- and that possibility looms in 2012.

Republican presidential hopeful Rick Santorum focused on Puerto Rico this week as he continues his bid for the White House. Puerto Rico -- which will have 23 delegates at the Republican National Convention in Tampa -- holds its primary on Sunday.

After addressing supporters in Louisiana after his wins in the Alabama and Mississippi primaries on Tuesday night, Santorum headed out to the island territory for campaign appearances on Wednesday and Thursday.

Floridas political history has been shaped by many different people -- the French, English, Spanish, Cuban, African-American, Puerto Rican, Yankees, Southerners and more. While Florida politics are not as Celtic-influenced as, say, those of Boston or New York, there have been a few leaders with Irish roots reigning over the Sunshine State.

One Florida politician in particular -- no, not former U.S. Rep. Andy Ireland -- deserves our attention on St. Patricks Day.

A poll from Rasmussen Reports unveiled on Wednesday finds Democrat incumbent U.S. Sen. Bill Nelson in jeopardy as he seeks a third term in November.

The poll of likely voters finds Republican U.S. Rep. Connie Mack with a solid lead over Nelson despite the incumbents four decades on the Florida political stage. Mack takes 43 percent, while Nelson trails with 36 percent, 16 percent remain undecided and 5 percent more back other candidates. A Rasmussen poll released last month found the race between the two a tie, with both candidates taking 41 percent each.

Earlier: Close Battles Loom in Alabama, Mississippi.

As the Republican presidential race turned to Alabama and Mississippi on Tuesday, two states almost assured to rally behind whoever emerges with the GOP nomination in November, Rick Santorum won both states by small margins over Newt Gingrich and Mitt Romney.

With 79 percent of the votes counted, Santorum won Alabama, which had 50 delegates on the line, with 35 percent, followed by Gingrich with 30 percent and Romney with 28 percent. Ron Paul trailed with 5 percent.