U.S. Republican presidential candidates are campaigning in Nevada, with billionaire real estate mogul Donald Trump looking to win his third straight nominating contest in Tuesday's party caucuses over his main rivals, Florida Senator Marco Rubio and Texas Senator Ted Cruz.
Recent political surveys show Trump, the brash New York developer and one-time casino magnate, with a significant lead in Nevada, the Western state that is the U.S. gambling hub.
A CNN/ORC poll conducted earlier this month showed him winning 45 percent support from Republican voters, with Rubio at 19 percent and Cruz at 17 percent.
Trump is coming off last weekend's convincing win in the South Carolina party primary, as Rubio edged Cruz for second place in the Atlantic coastal state.
U.S. political analysts are calling Trump, who has never been elected to public office, the confirmed leader for the Republican presidential nomination.
But surveys show a sizable group of Republican voters remain opposed to his candidacy, either because they do not think he can win the White House in November's national election against the leading Democratic contender, former Secretary of State Hillary Clinton, or because they do not believe his proclaimed support for a variety of conservative positions that most U.S. Republicans adhere to.
No vote for Trump
One prominent conservative pundit, Erick Erickson, said Monday he would never vote for Trump if he is the Republican nominee.
Years ago, Trump said he strongly supported abortion rights in the United States, but now tells voters he is pro-life, favoring a curb on the right of American women to the medical procedure.
But Erickson said he has become convinced that Trump's transformation on the issue "is a conversion of convenience."
A one-time local Republican official, Erickson said the party "will not deserve my support and will not get it if it chooses to nominate a pro-abortion liberal masquerading as a conservative."
Trump is set for a night-time rally Monday in Las Vegas after telling an interviewer on Sunday he expects to face Clinton in the November national election to pick the successor to President Barack Obama, who leaves office in January.
Cruz, a conservative agitator against both Republican and Democratic leaders in Washington, told a Nevada rally Sunday that he is the one "consistent conservative" in the race for the Republican nomination.
He attacked Trump for recently saying that he would be "neutral" in trying to broker Israel's relations with its Arab neighbors.
Cruz, a staunch supporter of the Jewish state, said, "I have no intention ... of being neutral."
Rubio told supporters he is the best Republican contender to unify the party's disparate religious, business and social conservative factions.
"I will unite this party. I will grow this party," Rubio said. "The Democrats do not want to run against me. I can't wait to run against them."
The next Democratic presidential nominating contest is in South Carolina on Saturday.
It is a party primary election that Clinton, the country's top diplomat from 2009 to 2013, is heavily favored to win over her remaining rival, Vermont Senator Bernie Sanders, a democratic socialist who has focused his campaign against the growing income inequality in the United States and the power of Wall Street financial titans.