Republican presidential candidate, former Pennsylvania senator Rick Santorum speaks during a stop at Panora Telecom Solutions, Monday, June 8, 2015, in Panora, Iowa. (AP Photo/Charlie Neibergall)

Rick Santorum, the deeply conservative former senator who won nearly a dozen contests in the 2012 race for the Republican nomination, is expected to announce Wednesday that he will suspend his latest and long-struggling run for the presidency.

Santorum is scheduled to appear Wednesday evening on Fox News Channel, where an aide said he will make “two major announcements.” According to several national Republicans familiar with his plans, he will discuss his decision to end his 2016 campaign and he will likely make an endorsement of one of his GOP rivals.

Santorum’s pending departure from the race, first reported by CNN, comes after a disappointing finish in Monday's Iowa caucuses, where he faced stiff competition for the support of the religious conservatives who four years ago were his base.

In 2012, the former Pennsylvania senator vaulted from relative obscurity -- and a crushing reelection loss in his home state -- to win the Iowa caucuses and 10 other states, only to fade after Mitt Romney clinched the GOP nomination.

Santorum becomes the third Republican to bow out of the crowded 2016 field since Monday's Iowa contest, with Sen. Rand Paul (Ky.) and former Arkansas governor Mike Huckabee also dropping out.

Santorum looked to build on his winning 2012 approach, making nearly 300 stops and visiting each of Iowa's 99 counties over the course of his latest campaign. But in the caucuses earlier this week, the candidate with the most Iowa-focused strategy received fewer votes than any candidate except former Virginia governor Jim Gilmore, who did not actively campaign in the state at all.

Santorum was one of a wave of hard-right contenders who believed that after losing two straight presidential elections behind more moderate nominees, GOP voters would turn to a candidate unflinching in ideology who can excite the party’s base.

But Huckabee, retired neurosurgeon Ben Carson, Sen. Ted Cruz (R-Tex.) and others occupied the political space that Santorum hoped to again call his own, drawing fervent backing from Christian activists, foreign-policy hawks and populist conservatives.

This time around, Santorum’s campaign also lacked many of the advantages that had helped fuel his 2012 insurgency – including most of the consultants who engineered it.

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His former campaign manager, Michael Biundo, signed on with Paul's campaign. Santorum's former Iowa aide, Chuck Laudner, who drove Santorum around the state in his “Chuck truck,” organized the state for Donald Trump. Two former spokesmen worked for Huckabee.

Among those still in Santorum’s camp were longtime confidant John Brabender and wealthy donor Foster Friess, whose money helped lift Santorum’s 2012 bid and who worked to raise funds for him again.

Santorum has for decades put his large family -- including severely disabled daughter Bella -- at the heart of his political life. At his campaign launch this spring near Pittsburgh, he appeared on stage alongside his wife Karen and most of their seven children.

He drew notice for speaking passionately about the need for the Republican Party to address the economic concerns of blue-collar workers. He called for an increase in the minimum wage, and criticized his party for focusing more on the needs of small business owners than on the issues affecting the people those businesses employ. “How are we going to win if 90 percent of Americans don't think we care at all?" he asked at a fall debate.

Like Huckabee, who won the Iowa caucuses in 2008, Santorum centered his 2012 strategy on reviving his support with conservatives in that state, where his victory propelled him up from the bottom of national polls after months of handshakes and grass-roots events.

Santorum spent months traveling across the state and to every county. It wasn’t enough: his support stayed mired in the low single digits in Iowa last year, and kept him off the main debate stage in the run-up to the first votes of the primary season.

Over the course of the campaign, he expressed mounting frustration with Republican officials and journalists over his relegation to the so-called “undercard” debate.

At his final debate in Iowa last month, he referred to Donald Trump as an “entertainer” and complained about the volume of media attention trained on the front-runner -- but refused to attack Trump directly. He and Huckabee had agreed to appear later that evening with the billionaire, who was skipping his own main stage debate appearance, at a rally Trump had organized to benefit veterans.

In his closing remarks at the debate, Santorum made one last plea to Iowans, pointing to the 700 speeches and town hall stops he had made in the state over the course of both his presidential campaigns.

“Here's what I'm asking you to do,” he said. “You're good people. You know good leaders. Lead. Pick the right person, not what the polls say," or who wealthy donors support. "Pick the leader you know is best for this country.”