Rivals now target Rubio; Trump calls for Iowa do-over

BOW, N.H. (AP) — While Donald Trump called for a do-over, Marco Rubio tried to capitalize on his moment in the spotlight today as the shrinking field of Republican presidential hopefuls jockeyed for position in a race rattled by an Iowa surprise.

Trump took to Twitter to vent his frustration with the Iowa results that landed him in second and gave fresh hope to Republicans hoping for a Trump-less race. Among those is Rubio, who seized on his third-place finish to cast himself as the sole "unifier" in a deeply fractured party and the man best positioned to beat a Democrat in November.

Rand Paul announced he was dropping out, and put a new crop of voters up for grabs for the other contenders. The Kentucky senator had tried to improve the GOP's popularity among younger voters and minorities. But his appeal never broadened much beyond the small group of libertarian-leaning Republicans who backed the previous White House bids of his father, Rep. Ron Paul.

Trump was still smarting over Iowa. Gone was the humble candidate who conceded to Ted Cruz on camera Monday night. In his place was a take-no-prisoners Twitter rant.

"Based on the fraud committed by Senator Ted Cruz during the Iowa Caucus, either a new election should take place or Cruz results nullified," Trump tweeted, following up on earlier Tweet claiming, "Ted Cruz didn't win Iowa, he stole it."

Trump has accused Cruz backers of spreading rumors that fellow candidate Ben Carson was dropping out of the race — even as caucusing was still underway.