(Bloomberg) —Texas Senator Ted Cruz returned to the Senate Tuesday, where he shouldn’t expect a warm embrace from one of the world’s most exclusive clubs. But to get much of anything done, they’re going to need him.

The freshman Texas senator, who came in second to Donald Trump in the epic fight for the Republican presidential nomination, returns with a higher profile, significant fundraising clout and, many Republicans believe, his eye on another race in 2020.

So if the Cruz of old could gum up the works, they know what a nomination runner-up could do if he doesn’t change his approach — especially one that former House Speaker John Boehner called “Lucifer in the flesh.”

“I think a lot of people here will always consider Ted an outsider,” Senator Lindsey Graham, who endorsed Cruz as a last-ditch ploy to defeat Trump, said Monday, adding it would be “up to Ted” if he wants to change his tactics.

“He didn’t come here to remain in the Senate. He came here to run for president,” John Cornyn of Texas, the No. 2 Republican in the Senate, recently told a Texas radio station.

Even though he suspended his presidential campaign last week, Cruz on Tuesday did not rule out restarting his bid if he wins the Nebraska primary. “I’m not holding my breath,” he told conservative radio host Glenn Beck, but said that if there is a path to victory, “we will certainly respond accordingly.”

Standing outside his Senate office on Tuesday afternoon, Cruz ruled out a third-party bid. But he did say that the campaign should be a “wake-up call” for Washington, adding that if fighting for the people makes him an outsider in the Senate, “then I will happily remain an outsider.”

This could complicate several issues on the docket, including the Puerto Rico debt crisis, a raft of spending bills and a criminal justice overhaul — all requiring delicate and bipartisan compromises at a moment when Republicans want to look like they can get things done ahead of the November election.

And Republican leaders would be far better off finding a way to accommodate Cruz, if possible, than have him resume plotting against them over pizza with members of the ultra-conservative House Freedom Caucus.

Ideological Purity

Cruz’s demands for purity — especially goading his party to shut down the government in 2013 in an unsuccessful bid to defund Obamacare — remain a major irritant with many of his fellow Republicans, who feel Cruz repeatedly boosted his own ambitions by pursuing strategies doomed to fail.

Count Senator Orrin Hatch of Utah as someone hoping Cruz has a change of approach.

“I hope that this experience will broaden his outlook and he’ll realize that it’s important to work with your colleagues,” Hatch said Monday. “You don’t have to kiss their rear ends but you sure need to respect their views as well as your own.”

Hatch, the senior Senate Republican, said he never thought Cruz would be president, and it’s now time to turn the page.

“Let’s forget the past. When Cruz comes back, if he’ll make some changes in his approach toward his colleagues, he’s a bright guy, he could be a great asset around here,” Hatch said.

“I just hope he’s not bitter about the whole thing,” he added.

Now that Cruz is back, he could frustrate Republican leaders. The first test will come on Puerto Rico, where Republican leaders face the difficult task of passing a financial restructuring package before another default expected July 1.

Spending Fights

On spending bills, Senate Majority Leader Mitch McConnell and his lieutenants have sought to minimize fights over partisan provisions, and they don’t want to risk a government shutdown.

But that’s exactly the kind of strategy Cruz ripped repeatedly on the campaign trail and in the Capitol as he slammed the bipartisan “Washington cartel.”

And even before Cruz returns, the debate in the Senate already faces a speed bump related to an amendment that aims to chip away at the Obama administration’s nuclear deal with Iran.

Cruz also will have to decide how hard to fight his friend Utah Senator Mike Lee’s bipartisan effort to overhaul mandatory minimum prison sentences, especially for nonviolent drug offenses. Lee was the first senator to endorse Cruz, but most never did, even when fellow candidate Senator Marco Rubio of Florida dropped out and Cruz was left as the most likely candidate to defeat Trump.

Strange Bedfellows

Cruz was an original sponsor of the criminal justice overhaul, but voted against a compromise version crafted by Judiciary Chairman Chuck Grassley of Iowa. The bill is backed by an unusual alliance of the White House and the conservative billionaire Koch brothers, Cornyn and No. 2 Democrat Richard J. Durbin of Illinois, New York Senator Chuck Schumer and many others. It’s a fragile bipartisan compromise that could get easily derailed by Cruz’s penchant for firebombing rhetoric on the Senate floor.

And that bill is sponsored by Cruz’s best friend in the Senate.

Cruz’s relationship with McConnell, meanwhile, may be beyond repair.

Cruz rejected suggestions during the campaign that he apologize to the Kentucky senator for calling him a liar on the Senate floor. The accusation came during a spat over the renewal of the Export-Import Bank, which was revived over Cruz’s strong objections. There could be more fireworks on that front, too, as McConnell has pushed Banking Chairman Richard Shelby of Alabama to move nominees for the bank’s board to the Senate floor. Shelby has so far refused, saying he opposes the bank.

Outsider Status

While Cruz is no longer running for president, he may not have much incentive to change.

He will be favored to win re-election to the Senate in 2018, and his outsider credentials got him where he is today.

Susan Collins of Maine, who was sharply critical of Cruz during the shutdown, declined to offer up advice.

“I’ve never known Senator Cruz to ask me for advice, so I’m not about to give him unsolicited advice,” she said Monday. “We look forward to seeing him tomorrow.”

The other three Republican senators who ran for president have each gone their own way since returning from the campaign trail. Rand Paul of Kentucky is backing Trump and running for re-election, but has been quiet inside the Senate. Rubio has been, if anything, rejuvenated, becoming a leading voice in his party for Zika funding and a Puerto Rico overhaul.

And then there’s Graham of South Carolina, who joked earlier this year that the Senate would refuse to convict anyone who murdered Cruz and likened him to poison, only to later endorse him in a doomed effort to stop Trump.