A committee at the Republican National Convention defeated the effort by anti-Donald Trump conservatives to derail the presumptive GOP nominee’s drive to secure the party’s nomination, voting late Thursday to rebuff their plans to let delegates vote for any candidate they’d like.

Party officials used a voice vote to reject a proposal by Colorado delegate Kendal Unruh to let delegates “cast a vote of conscience” and abandon the candidate they had been committed too through the state primaries or caucuses.

The amendment became a focal point of furious lobbying that’s pitted the so-called Never Trump movement against Trump’s campaign and top leaders of the Republican Party. On a 112-member rules panel dominated by party and Trump loyalists, the outcome was expected.

Unruh expected to collect signatures from 28 members to bring a vote to unbind the delegates on the convention floor in Cleveland next week. However, she was only able to collect 21.

She encountered overwhelming opposition from delegates arguing that it would be unthinkable for the party to abandon Trump after he overwhelmingly won GOP primaries and caucuses and garnered more than 13 million votes.

"You want to ignore what is really the grassroots, which is millions and millions and millions of voters who voted for Donald Trump," said Stephen Munisteri, a delegate and leading GOP figure from Texas.

He added, "The only way to advance the conservative cause is through a strong Republican Party that is united to defeat Hillary Clinton and the Democrats this fall."

For good measure, the rules panel also approved language specifically stating that party rules allow delegates to be "bound" to candidates.

Despite their defeat, anti-Trump delegates say they believe current rules already free delegates to support anybody and have planned to contest balloting when the convention votes for its nominee next week.

While on a path to near-certain victory, Trump has drawn bitter opposition from Republicans who say he's not conservative and is an inept campaigner whose harsh statements will cause his defeat and losses by GOP candidates for Congress and elsewhere.

Earlier Thursday, talks between top party officials and recalcitrant conservatives broke down, increasing the odds of nationally televised clashes during next week's sessions on other GOP rules, a faceoff leaders have been hoping to avoid.

As Thursday's negotiations foundered, the alliance between the Trump campaign and leaders of the Republican National Committee showed its muscle and began rejecting conservatives' attempts to revamp party rules.

In one showdown, the rules committee voted 86-23 to reject an effort by conservatives to eliminate the RNC's ability to change party rules in years between national conventions. In another, the panel used a voice vote to defeat a plan to bar members of the RNC from being lobbyists — a profession that employs many of them in their home states — though it would have exempted lobbyists for nonprofit organizations.

In a gesture to conservatives, the rules panel voted to create a commission that by 2018 could propose changes to the GOP's presidential nominating process, which came under intense fire this year. Trump called the system "rigged" early on, and his opponents have demanded more power for delegates to select a fresh nominee.

The closed-door negotiations were aimed at finding middle ground that would have increased the chances for a smoothly functioning four-day gathering next week, averting televised battles among members of a party whose likely presidential candidate has already proven divisive. There's been talk of some Trump foes walking out of the convention if they feel they've been treated unfairly, a spectacle top Republicans would love to avoid.

But by late afternoon, Ken Cuccinelli — a leader of the conservatives who was an adviser to Cruz's presidential campaign — said GOP leaders he was negotiating with told him, "Sorry, we don't have a deal."

Those talks focused on conservatives' proposals, aimed at appealing to grassroots conservatives, that would take power from the Republican National Committee — consisting of 168 party leaders from around the country — and its chairman, who is currently Reince Priebus.

Both sides agreed that the bargaining broke down over an effort by conservatives to provide extra convention delegates to states with primaries closed to independent and Democratic voters, many of whom flocked to Trump in this year's voting.

Cuccinelli said he would win enough support — 28 of the rules committee's 112 members — to be allowed votes on several of his proposals by the full convention.

RNC chief spokesman Sean Spicer said he would not.

Fox News’ James Rosen, Jennifer Hickey and the Associated Press contributed to this report.