Republican insiders predicted Wednesday that Senate Majority Leader Mitch McConnell wouldn't back down from his pledge to block President Obama's expected pick to succeed the late conservative justice Antonin Scalia on the Supreme Court.

Some Republicans have questioned the wisdom of the Kentucky Republican's quick move announcing that Scalia's successor shouldn't be appointed until the voters weigh in this November and the next president is inaugurated. Senate Minority Leader Harry Reid, D-Nev., predicted that McConnell would eventually acquiesce and permit the Senate to vote on Obama's nominee.

But Republican operatives familiar with McConnell's thinking and closely aligned with GOP senators said they expect the blockade to hold. The stakes of letting the now-evenly divided nine-member high court swing liberal with the confirmation of what would be Obama's third nominee, and the political repercussions for doing so, are enough to keep most Republicans on board with McConnell's plan.

"There is no way to move a nomination past a filibuster by true conservatives," one GOP source said. "Republican moderates in the Senate do not want to vote because they will alienate their base if they vote for cloture."

Battle lines are being drawn in the race for the White House, functioning as another check on Republicans who might advocate that the Senate consider Obama's eventual Supreme Court nominee. Leading candidates like Sens. Ted Cruz of Texas and Marco Rubio of Florida back McConnell's decision to obstruct the president during the final 11 months of his presidency. Both presidential contenders are running campaign ads highlighting the court as an issue.

Other Republican candidates, including former Florida Gov. Jeb Bush and front-runner Donald Trump, the New York celebrity businessman, also are on board with McConnell's plan. Clinching the opposition to an Obama Supreme Court pick, however, is the support McConnell quickly received from a few of his colleagues who are running for re-election in competitive states and could turn out to be quite vulnerable to Democratic challenges.

"We're in the midst of a consequential presidential election year, and Americans deserve an opportunity to weigh in given the significant implications this nomination could have for the Supreme Court and the country for decades to come," Sen. Kelly Ayotte, R-N.H., said in a statement issued on Sunday, on the day after Scalia's death was made public. "I believe the Senate should not move forward with the confirmation process until the American people have spoken by electing a new president."

Ayotte is running in a close race in a competitive swing battleground that has leaned Democratic in recent presidential elections. "It will obviously ratchet up partisan intensity on both sides," a Republican campaign strategist said, regarding the Supreme Court. "But in a presidential year the increase should be marginal."

The country is split on how to handle the Supreme Court vacancy, according to an NBC News/Wall Street Journal poll released on Wednesday. Forty-three percent of Americans believe the Senate should act this year on Obama's nominee; 42 percent favor waiting and letting his successor filling the opening; 15 percent have no opinion. President Obama has made clear that he expects the Senate hold a confirmation vote on his nominee.

Conservatives interested in maintaining an edge in the public relations fight and protecting the Senate's prerogative to block Obama's nominee are kicking around ideas as to how they would prefer Senate Republicans frame the issue. Their ideas include providing Obama with a list of conservative jurists that would be acceptable. Democrats see a political opening in the GOP gambit.

"I first of all think that they're going to cave in," Reid said, during an event in Reno, Nev. "I think the president's going to give us a nominee that's a good one and I think they're going to have to hold hearings and have a vote."