Donald Trump came in first in the South Carolina primary, but Marco Rubio and Ted Cruz celebrated in their speeches that night, too. Former Florida governor Jeb Bush took fourth place and ended his campaign. (Sarah Parnass/The Washington Post)

For months, Republican Sens. Ted Cruz (Tex.) and Marco Rubio (Fla.) have thrown sharp elbows, traded petty insults and compiled thick opposition research files on one another in anticipation of the moment they would find themselves in a knockout fight for a showdown with Donald Trump.

That moment has arrived.

In South Carolina’s primary on Saturday, Rubio held a slight lead over Cruz in their tight battle for second place behind Trump after one of the nastiest weeks of their bitter rivalry. The two young Cuban American senators finished well ahead of Jeb Bush, who suspended his campaign after a disappointing showing, John Kasich and Ben Carson in this state, effectively paring the GOP presidential nominating contest down to a three-man race and raising the stakes in their one-on-one battle.

Rubio will now look to consolidate the mainstream wing of the Republican Party, which is already beginning to line up behind him and will likely continue to after Bush’s departure from the race. His playbook against Cruz is a straightforward one: Cast his Texas colleague as dishonest and assail his record on national security as weak and contrast that with his sunnier “new American century” message.

“After tonight, this has become a three-person race, and we will win,” said Rubio in a speech to supporters Saturday night.

South Carolina Republican primary exit poll results

In his speech, Rubio commended Bush and praised him for “running a campaign based on ideas.” Cruz lauded Bush for bringing “honor and dignity” to the race.

Cruz told a cheering crowd that the race for second place remains a toss-up.

“Right now we are effectively tied for second place, but each time defying expectations,” Cruz said. “The screaming you hear now from across the Potomac is the Washington cartel in full terror that the conservative grass-roots are rising up.”

Cruz’s campaign manager, Jeff Roe, said the race is shifting to a national campaign with a top tier and lower tier. “It’s clear the top tier, there’s three people. We call it three wide going into Talladega,” Roe said.

Cruz told supporters he is the only candidate who can take on Trump. “This is the only campaign that has beaten, and can beat, Donald Trump,” said the senator, who edged Trump in the Iowa caucuses.

Cruz is aiming for a strong showing in a slate of Southern states on March 1. His anti-Rubio scheme: Present the Floridian as a centrist masquerading as a conservative on a range of issues, most notably immigration.

The Cruz-Rubio struggle will pitch quickly to Nevada, where Rubio and Cruz plan to campaign hard in the coming days ahead of Tuesday’s caucuses.

Here in South Carolina, where politics is known for being a bare-knuckle fight, the two senators exchanged insults and near-constant accusations.

Trump’s victory became clear shortly after polls closed, meaning that much of the night’s intrigue centered on the battle for second place. At Rubio’s watch party, supporters eagerly kept up with the results as they sipped beer and wine.

At Cruz’s party in a conference room at the state fairgrounds, fewer than two miles from where Rubio’s supporters gathered, backers sipped sweet tea and ate popcorn and cheddar cheese goldfish. No alcohol was served. Supporters wearing stickers that read “Choose Cruz” milled around, chatted and watched Fox news on two large screens in the front of the room, the audio feed cutting in and out with country music.

Rubio got a new lease on his campaign life in South Carolina after a humiliating fifth-place showing in New Hampshire. He adopted a strategy of opening himself up more to the media, collecting key endorsements from state officials and cautiously avoiding questions from voters in the closing days.

The Florida senator barnstormed the state during the final 48 hours of the race alongside Gov. Nikki Haley, Sen. Tim Scott (R-S.C.) and Rep. Trey Gowdy (R-S.C.), a youthful and racially diverse coalition of politicians Haley likened to a “Benetton commercial.” Rubio mostly held rallies — not town halls where audience members are invited to ask questions.

He and his campaign accused Cruz and his team of not telling the truth on matters ranging from Cruz’s talking points to a doctored photograph showing Rubio and President Obama shaking hands.

Rubio also portrayed Cruz as weak on national security by virtue of his vote in support of a budget plan forwarded by libertarian-leaning Sen. Rand Paul (R-Ky.).

Cruz countered by arguing that Rubio was trying to divert attention from his record, which the Texan has disparaged as insufficiently conservative. His campaign attacked Rubio for backing out of a conservative confab and argued that he supports “amnesty” for illegal immigrants.

Cruz tried to distinguish his view of the military from Rubio’s, arguing that Rubio would be too quick to jump into foreign adventures. Cruz attempted to link Rubio with the foreign policy of President Obama, citing the fact that Rubio voted to confirm John F. Kerry as secretary of state.

Cruz has spent his entire campaign assiduously courting evangelical Christians, and expected to do well among them here — at least 300 South Carolina pastors endorsed Cruz. But according to exit polls, Trump narrowly edged Cruz with evangelical Christians, a disappointing showing for a candidate who spent months coming to church services and meeting with pastors here.

The Cruz campaign attempted to replicate the ground game that propelled it to victory in Iowa earlier this month, relying on more than 15,000 volunteers who knocked on 100,000 doors in the state over the past three weeks and made 56,000 phone calls Friday, according to the campaign. A constellation of super PACs supporting the Texas Republican also deployed a robust door-knocking effort, fanning out across the Palmetto State.

Beyond Nevada, Cruz hopes to do well in the so-called “SEC Primary” a collection of Southern states that will vote on March 1.

Cruz has said the South could prove to be a “firewall” for his campaign, which has spent months pouring resources and time into the delegate-rich region. Cruz blitzed across the South twice last year, holding large, slickly-produced rallies that felt more like those in a general election.

“We’re going to have a big night on March 1, in an electoral map that favors us,” said Roe, Cruz’s campaign manager. “And then after that we’re going to go and battle out in the winner-take-all states . . . and decide who the nominee is.”

Roe insisted that the race is shifting toward a national one focused much less on rooting out individual voters and more on broad messaging to a wide swath of the electorate.

“There were 79,000 people choosing between us and Trump in the last four days,” Roe said. “We were calling them. We know them. Now you don’t do that on Super Tuesday. Super Tuesday becomes much more of a narrative-based campaign, much more of a national campaign.”

Rubio does not have as obvious a batch of states where he is poised to perform as well, but he stands to gain the most of any candidate from Bush’s exit from the campaign. Many in Bush’s deep donor pool are expected to think seriously about supporting Rubio now.

Kasich has signaled that he plans to stick around, eyeing March contests in Midwestern states such as Michigan and his home state of Ohio. If he does, that would be a blow to Rubio.

Rubio strategists are trying to stay within shouting distance of Trump in the states leading up to March 15, when most states will begin to allocate their delegates on a winner-take-all basis. His aides believe a winnowed field will redirect more support to him than to either Trump or Cruz.

That shrinking started Saturday with Bush’s exit. At Cruz’s watch party, a cheer went up when Bush announced he was suspending his campaign. The same thing happened at Rubio headquarters.