SCOTT AUDETTE REUTERS Donald Trump has mainstream Republicans in a tizzy as he's closer to becoming party's presidential nominee

"He [Rubio] referred to my hands as small, saying then something else must be small, I guarantee you there is no problem, I guarantee it".

Either they must embrace a Romney-led attempt to overturn the democratically-expressed will of millions of voters and risk alienating Trump supporters who, if they reject the GOP, could effectively hand the election to the Democrats.

Candidates traded insults, yelling, screaming, interrupting and mean talk at the latest Republican Party debate. Here & Now's Robin Young speaks with NPR political reporter Scott Detrow about the debate and what it all means for the Republican Party.

The path Romney and his allies have chosen leaves Republicans with a dilemma, assuming Trump extends his march toward the nomination in coming primaries and caucuses - and there is little reason to think he won't.

Anxious about Trump, a new group called the Committee to Draft Speaker Ryan filed papers with the Federal Election Commission on Thursday, seeking to raise money to push Ryan as a Republican alternative. SUPPORT FOR CLINTON Cruz, a US senator from Texas, suggested Trump would be the wrong candidate to send into battle against Democratic front-runner Hillary Clinton because he has supported her financially in the past. The Florida senator said that if any candidate "deserved" to be personally attacked, it was Trump because of how much he attacks others. Clinton has attacked controversial Trump before also.

Trump wasted little time in striking back, calling Romney a "choke artist" and assailing him for "begging" for an endorsement, only to lose to Obama four years ago.

When asked about the timing of Thursday's speech, Romney said he simply "couldn't stand silent anymore" as the GOP race reached a "new low in presidential politics".

He said he had changed his own mind to support admitting more highly skilled workers from overseas, adding matter-of-factly, "I'm changing".

Mr Rubio said that he is committed to his party and therefore would support the nominee.

This time, Trump showed up.

Rubio on water crisis in Flint, Michigan: "I give the governor credit, he took responsibility for what happened".

Donald Trump responds at Thursday's Republican debate to Marco Rubio's criticism of his hands, and the inference.

No, no, the people who can save this party are Ted Cruz, Marco Rubio, or John Kasich.

Trump's response: "I have a very strong core". Rubio and Kasich will need to win at home as well when Florida and OH vote on March 15. "But I've never seen a successful person who wasn't flexible, who didn't have a certain degree of flexibility". Trump, who dismissed Kelly as a "lightweight" and a "bimbo", ended up boycotting a subsequent Fox debate, claiming the network was unfair.