Five things to watch for at Republican debate in Miami
© Getty Images

It’s debate night in Miami, where the four Republicans standing in the presidential race will square off ahead of the critical March 15 primary in Florida, where one of them will walk off with 99 delegates. 

Front-runner Donald TrumpDonald John TrumpFlynn to campaign for Montana GOP Senate candidate Trump considering pardon for boxing legend after call from Sylvester Stallone Decline in EPA enforcement won't keep climate bill from coming MORE has 458 delegates and is more than one-third of the way to clinching the nomination, which requires 1,237 delegates. 

Sen. Ted CruzRafael (Ted) Edward CruzCruz's Dem challenger slams Time piece praising Trump Race for Republican Speaker rare chance to unify party for election 32 male senators back Senate women's calls to change harassment rules MORE (R-Texas) is Trump’s closest competitor, with 359 delegates, while Sen. Marco RubioMarco Antonio RubioStudents gather outside White House after walkout to protest gun violence Overnight Energy: Senate confirms Bridenstine as NASA chief | Watchdog probes Pruitt’s use of security detail | Emails shine light on EPA science policy changes Senate confirms Trump’s pick to lead NASA MORE (R-Fla.) and Ohio Gov. John Kasich are desperate to survive. 

Kasich needs a win Tuesday in Ohio, where he leads some polls and could take in 66 delegates with a victory. 

Rubio is in more dire straights, making Thursday’s debate a critical moment for him. He must win Florida, but trails Trump in most polls. 

Trump says he’s going for the knockout blow, and Cruz will similarly be seeking to squeeze Rubio out to set up a two-man race. 

Here are five things to watch for at the debate hosted by CNN, Salem Radio and The Washington Times.

Will the tone turn from nasty to nice?

Many Republicans were embarrassed by the personal insults, bickering and low-brow turn of the GOP debate a week ago in Detroit.

That debate will be remembered for Trump responding to criticism from Rubio that he has “small hands” by referencing the size of his manhood.

A focus group conducted by Republican pollster Frank Luntz described the proceedings as “childish” and “embarrassing,” while a former aide to Rick Perry fretted that his party had committed suicide on national television.

Democrats have been gleeful over the mudslinging, believing it puts them in a strong position for the general election.

Rubio appears ready to discard his strategy of matching Trump insult for insult. The Florida senator has acknowledged that his “kids were embarrassed by it” and that it made his wife uncomfortable.

It also didn’t seem to work. 

Trump stampeded through Tuesday’s primaries, while Rubio didn’t win a single delegate.

Will Cruz and Trump call on Rubio to drop out?

Rubio is being challenged on a daily basis about why he is still in the race, and Trump and Cruz have both called on him to drop out. 

If they repeat those calls on the debate stage, it will set up a dramatic moment. 

Kasich faces a similar threat, though his standing in Ohio polls gives him a better argument. 

He’s also repeatedly acknowledged he’s angling for a seat at the table of a contested convention, which would take place if no candidate gets to 1,237 delegates.

The narrative is turning against both men, as many Republicans — even some who have in the past recoiled at the thought of a Cruz nomination — are coming around to the idea that the others need to fall away for the Texas senator to take Trump on one-on-one.

Will there be a softer tone on immigration?

Democrats are running for the Hispanic vote, which Republicans worry could cost them the election if Trump is their nominee. 

The billionire's controversial descriptions of illegal immigrants and his claim that he’ll build a wall along the southern border that Mexico will pay for has raised questions about whether he’d lose 80 percent of Hispanic voters. (President Obama won more than 70 percent in 2008 and 2012.) 

Since Thursday’s debate is in Miami, Trump may seek a different tone — especially because he now needs to have an eye on the general election. 

At the last debate, he already announced a “softening” os his stance on visas for highly skilled immigrant workers.

But Trump may not be able to go too far while sharing a stage with Cruz, who will be looking for any sign of weakness from the front-runner to reclaim the mantle of the most hawkish Republican on border security.

Expect the administration’s policy toward Cuba, as well as the Puerto Rican debt crisis, to also be in focus at the debate. Those issues could set Rubio up for a couple of strong moments. 

Ganging up on Trump

The hour is getting late for those seeking to stop Trump. If he wins Florida and Ohio on Tuesday, many political analysts believe the game will effectively be over.

Trump has been the subject of relentless assault from outside groups on the airwaves in both states, but those attacks have failed to slow him down.

The Rubio and Cruz campaigns have been digging through opposition research, signaling they’ll make the case against the celebrity tycoon by dredging up controversial aspects of his decades-long business career.

Expect Trump to have to answer for the university, the vodka, the steaks, the beauty pageants, the bankruptcies, the taxes and a host of other issues that go to the core of his business record.

Are Rubio and Cruz sitting on any bombshells? Will it matter?

Will Trump shift to the general? 

In recent weeks, Trump has begun looking ahead to a potential general election match-up with Hillary ClintonHillary Diane Rodham ClintonGeorge HW Bush wears 'book socks' to Barbara Bush's funeral to honor her passion for literacy Obamas, Clintons to attend funeral of Barbara Bush Hillary Clinton to fundraise in DC for public charter high school MORE.

He has talked about uniting the GOP and helping down-ticket Republicans, and has highlighted conversations with party leaders, like Speaker Paul RyanPaul Davis RyanScalise released from hospital after planned surgery GOP sold Americans a bill of goods with tax reform law Impeaching Rosenstein? Some Republicans are talking about it MORE (R-Wis.).

That might mean a dialed-back performance from the front-runner, who has been accused of acting un-presidential.

Trump could be seeking to convince the moderates in the GOP that he won’t embarrass them or face-plant in the general election.

Still, Trump is unpredictable, and has said he’s seeking the “knockout” blow against Rubio, in particular.

He’s likely to be under furious attack as he stands sandwiched between Rubio and Cruz, and the debate may offer another challenge of his ability to keep cool while under fire.