Donald Trump could take a giant step on Tuesday toward securing the Republican presidential nomination if he wins the Florida and Ohio primaries, which would intensify pressure for rivals from the party establishment to pull out of the race.
Trump has the potential to sweep five big states holding party primary contests for the November election: Florida, Ohio, Illinois, North Carolina and Missouri. The Republican front-runner could knock out his two mainstream rivals, Ohio Governor John Kasich and U.S. SenatorMarco Rubio of Florida, if he wins their states.
The 69-year-old billionaire businessman has a significant lead over Rubio in opinion polls in Florida, but is neck and neck with Kasich in Ohio. Any win by either Rubio, Kasich or U.S. Senator Ted Cruz, 45, of Texas would give at least a small degree of hope to Republicans battling to deny Trump the nomination.
Trump said on Tuesday that his momentum was already drawing in establishment Republicans who had previously balked at his candidacy but now see him as the likely nominee.
"They're already calling," the New Yorker told NBC's "Today" show, without naming names. "The biggest people in the party are calling."
Trump victories in the five states could make what once seemed inconceivable a strong probability, putting the former reality TV star - who has vowed to deport 11 million illegal immigrants, impose some protectionist trade policies and temporarily ban Muslims from entering the country - on a glide path to being the Republican Party's presidential candidate in November.
Trump drew first blood on Tuesday, winning the Northern Mariana Islands caucuses with almost 73 percent of the vote. The win in the U.S. Pacific commonwealth gave him nine delegates.
On the Democratic side, former Secretary of State Hillary Clinton, 68, could put some distance between herself and rival Bernie Sanders, 74, a U.S. senator from Vermont, in Tuesday's Democratic primaries.
Opinion polls gave her a big lead in Florida and North Carolina, but showed Sanders gaining ground in Ohio, Illinois and Missouri, a possibly worrisome sign for Clinton after Sanders' surprise victory in Michigan a week ago.
"I voted for Bernie because I want to see a real change to how we do things in this country," Jackie Zydeck, 52, an attorney for the federal government, said after voting in Chicago's liberal Albany Park neighborhood.
"I like his single-payer healthcare idea; I like his ideas about taxes," Zydeck said.
'Optimism Over Pessimism'
Trump held rallies in Florida, Ohio and North Carolina on Monday and said establishment Republicans who have labored to stop his outsider candidacy needed to rally to his cause.
An outbreak of clashes between Trump supporters and protesters that forced him to cancel a rally in Chicago on Friday, and scattered protests at some of his campaign events this week have prompted more concerns from mainstream party figures.
U.S. House of Representatives Speaker Paul Ryan on Tuesday condemned efforts to disrupt political rallies, but said all presidential candidates must bear responsibility for helping curb violence at campaign events and creating a less hostile atmosphere.
"All candidates have an obligation to do what they can do ... provide an atmosphere of harmony, to reduce violence, to not incite violence," Ryan told reporters.
The Republican establishment's only real hope for stopping Trump is to deny him the 1,237 delegates needed for the nomination, even though he may win a majority of them. That would extend the battle to the party's nominating convention in July in Cleveland.
"I believe the ideal outcome in this campaign is to have someone not named Donald Trump coalesce the party with 1,237 delegates and go on to defeat Hillary Clinton in November,"Rubio, 44, told Fox News. "If he's the nominee, he is not going to be able to unite the party. In fact, I think he'll bitterly divide it."
Kasich, 63, slammed Trump for a series of comments he has made over the years that disparage women. Those remarks featured in an ad released this week by an anti-Trump Republican Super PAC group.
"I have two daughters. They see this stuff; what do you think they think?" Kasich told reporters in Westerville, Ohio.