WASHINGTON ― Sen. Ted Cruz (R-Texas), once a bitter rival of President-elect Donald Trump, called on a room full of conservative attorneys and law students to serve in Trump’s administration.

At the same time, Cruz declined to declare his own interest in filling the Supreme Court seat vacated by the late Justice Antonin Scalia.

“Because of the election, we here in this room have an enormous opportunity to help revive and restore our nation,” Cruz told a packed crowd at the conservative Federalist Society’s National Lawyers Convention in Washington, D.C., on Friday.

“This gathering may well be the single largest collection of individuals who are likely to serve in the new administration,” Cruz said. “If you look down the aisles at your friends and neighbors and colleagues, I have great confidence that we are collectively looking at scores of federal judges.”

Cruz, the runner-up in the race for the Republican presidential nomination and one of the most prominent conservative jurists in the country, went on to describe opportunities for conservative lawyers to staff federal agencies like the Department of Justice.

Cruz’s stressed that the dedicated movement conservatives who were most supportive of his presidential candidacy should serve the government, in particular to make sure that the ruling Republicans remain faithful to conservative values. The implication of Cruz’s comments was that President-elect Trump, whose conservative credentials Cruz has criticized, could not necessarily be trusted to adhere to these small-government ideals on his own.

“For those that choose to serve, who have the opportunity to serve, we could not do better than to follow the example that was blazed by Justice Scalia,” Cruz said, drawing loud applause. (Cruz himself was once a law clerk for the late Chief Justice William Rehnquist.)

Cruz peppered his remarks with fond memories of Scalia and lessons from his career, noting that deceased Supreme Court Justice started at federal agencies.

“It was in positions like these where he met Leviathan face to face,” Cruz said, using a Hobbesian moniker for the federal bureaucracy.

He emphasized that it would not be easy to roll back regulations and minimize federal interference in the private sector from within the federal government ― but that it was necessary nonetheless.

“As they say in politics, ‘It ain’t bean bag.’ But we need all hands on deck,” Cruz said.

Later, Cruz demurred when asked by a conference attendee whether he was interested in filling Scalia’s seat, insisting only that he was committed to filling the seat with a staunchly conservative jurist. But he did not categorically rule it out, either.

“History is long and can take unexpected paths. I think it is absolutely vital that that seat and every other seat that becomes vacant on the Court be filled by a principled constitutionalist who will be faithful to the law and who will check their own policy preferences at the door,” Cruz said.

“I have right now the privilege of serving in the United States Senate and representing 27 million Texans,” he said. “That is a privilege and responsibility I take very, very seriously.”

The Texas senator’s speech was the culmination of a remarkable about-face for a political adversary whose antipathy to Trump ran so deep that he refused to endorse the nominee in a primetime speech at the Republican National Convention. Trump had, over the course of a nasty primary campaign, insinuated that Cruz’s wife Heidi was ugly, suggested without basis that Cruz’s father was involved in John F. Kennedy’s assassination and questioned whether the Canadian-born senator was eligible for the presidency.

Cruz ultimately endorsed Trump in August and subsequently volunteered for his campaign.

But Cruz’s remarks on Friday were also a reminder that he continues to enjoy a substantial political following of his own, not least among the ranks of Federalist Society lawyers with whom he was close long before he was a national figure. He got a rockstar reception at the gathering of conservative legal minds and stuck around after his speech to take photos with dozens of attendees.

For a conservative legal scholar like Cruz, the importance of controlling judicial appointments clearly played a large role in his decision to embrace Trump’s candidacy. In his Friday remarks to the Federalist Society’s convention, Cruz ticked off the conservative priorities that would have been erased if Hillary Clinton had been election and allowed to reshape the Supreme Court. Those include the liberalization of campaign finance laws, so-called religious liberty laws that ensure conservative believers’ rights to discriminate against LGBTQ Americans and the right to administer the death penalty, among other measures.

Although Trump passed over Cruz for the position of attorney general, Cruz expressed his satisfaction with the choice of Sen. Jeff Sessions (R-Ala.) to the top law enforcement post.

“[Sessions] is a committed and deeply principled conservative and if those who serve in this administration have even a fraction of his integrity and commitment to principle, we are going to see an administration that does remarkable things for the people of this country,” Cruz said.