MANCHESTER, N.H. (AP) -- A victorious Ted Cruz and buoyant Marco Rubio emerged from Iowa with compelling claims to the outsider and mainstream mantles in the fractured Republican primary, as the presidential race shifted overnight to New Hampshire. Democrats were girding for a protracted slugfest between Bernie Sanders and Hillary Clinton, locked in a virtual tie.

Donald Trump, uncharacteristically humble after a second-place Iowa finish, was headed for far friendlier territory in New Hampshire, where the billionaire firebrand had a commanding lead.

Amid historically large turnout in Iowa, the unexpected benefactor was Rubio, who came within striking distance of Trump. Republicans had already been looking to New Hampshire to winnow their congested field, and the Florida senator's strong showing bolsters his case that Republicans should coalesce behind him as the mainstream alternative to the rowdier Trump or Cruz.

"We have taken the first step, but an important step, to winning the nomination," Rubio told supporters in Des Moines.

Monday's Democratic contest was a cliffhanger - "The results tonight are the closest in Iowa Democratic caucus history," said state party chairman Andy McGuire - a far cry from the coronation for Clinton that most Democrats once expected.

Even with an elaborate campaign operation and backing from most Democratic Party leaders, Clinton was unable to stem a flood of enthusiasm from young and liberal voters for Sanders, the eccentric Vermont senator whose viability in a general election is still deeply questioned.

Cruz, the Texas conservative known for his scorched-earth approach to compromise, hoped his triumph in the Iowa caucuses would bolster his standing as the top choice of Republicans seeking an agitator to upend the legacy of eight years under President Barack Obama. Having run a textbook Iowa campaign targeting rural and evangelical voters, Cruz faced a steeper climb in New Hampshire, with its tradition of favoring more mainstream candidates.

"We've built our campaign as a movement for Americans to organize, rallying and banding together against the disaster of the Washington cartel," Cruz told The Associated Press as he made his way to New Hampshire.

Despite falling short of victory, Trump proved he could transform many of his die-hard fans into actual voters - the key question facing his campaign heading into Monday's voting. Yet the results raised an equally curious question: how Trump, who's branded himself as a reliable winner, can handle being a loser.

Thanking supporters at a rally, Trump displayed a rare hint of modesty as he congratulated Cruz and the other Republicans.