Texas Sen. Ted Cruz, a past and perhaps future presidential contender, spent the past year proving he can work well with Republican colleagues he’s butted heads with in the past.

Now less than a month out from Texas’s primary, where Cruz faces little serious opposition, that cooperation appears to be dissipating as he pushes his party toward a tough conservative agenda in Washington.

Cruz boasted Wednesday to a Texas audience that he rallied conservatives in the Senate to repeal Obamacare’s individual mandate in their tax bill, against the will of party leaders, who feared it could sink tax reform, their bigger policy priority. He’s also pushing his party to revisit efforts to repeal Obamacare this year, even though GOP leaders have moved on to other projects they believe will garner Democratic support in a chamber that’s been paralyzed by partisanship.

Speaking to members of the Texas Water Conservation Association in Washington, Cruz, who famously led a 2013 government shutdown over Obamacare, channeled his old self.

He called on GOP colleagues to use every option they have over the next ten months, including getting rid of the filibuster, to deliver on campaign promises they made in 2016.

“We’re at a time of enormous opportunity, I think, and enormous transition. We’ve got a Republican president, Republican majorities in both houses of Congress, and an opportunity to do an awful lot,” said Cruz.

“When we started the year in 2017 in my mind there were four big priorities… If we failed to deliver on any of those four, it would be a heartbreaking opportunity,” said Cruz.

He said Republicans had promised voters tax reform, regulatory reform, Obamacare repeal and more conservative judges.

The party has already notched some victories on those goals, with a major tax bill in December, a swath of Obama era environmental regulations repealed under the Congressional Review Act early in 2017 and Senate confirmations for a number of key judicial appointees.

Faced with a narrow majority in the Senate, where Republicans hold 51 seats but need 60 to advance major legislation, party leaders have now turned their focus to areas where they can work with Democrats. That became notably apparent Wednesday as Republican and Democratic leaders agreed on a two-year budget deal.

Asked about the year ahead on a press call with local reporters, Texas’s senior senator John Cornyn, who serves as the second-ranking Senate Republican, listed infrastructure and immigration bill among the next priorities. He said Democrats should be motivated to work with Republicans in the coming year, since 10 Democratic seats are up this year in states Trump won in 2016.

“I’m optimistic that we pick up some Senate seats in 2018, particularly if [Democrats] play politics and don’t engage in some bipartisan governance,” said Cornyn.

President Donald Trump went further in his State of the Union Address last month, saying he was “extending an open hand to work with members of both parties — Democrats and Republicans.” He called for their help on an immigration bill and said his White House had been meeting with both parties regularly.

Cruz, meanwhile, wants Republican to act on their own.

Last fall he introduced a tax plan that would rely only on Republican votes, while Trump was talking about working with Democrats.

The eventual tax bill different greatly from Cruz’s plan, but no Democrats voted for its passage.

“I’ve been urging using more and more tools that can pass things on 51 [votes] because… I can’t go home to Texans and say, ‘Well gosh, Democrats are opposing everything so we’re going to do nothing,’” Cruz said Wednesday.

Among those tools, Cruz listed the Congressional Review Act, which allows Congress to vote to strike down rules made by the White House within a short span of time after their creation.

He also pointed to a legislative procedure called reconciliation, which allows lawmakers to pass legislation with a simple majority if it’s related to the budget. That tool allowed the GOP to pass tax reform without the help of Senate Democrats.

Cruz would like to end the Senate’s legislative filibuster, a move many members of his own party would not support. The filibuster requires 60 votes to advance major Senate legislation, forcing the chamber to move more slowly than the House, where a simple majority can limit debate.

Cruz acknowledged that change wasn’t likely to happen, because it lacks the support of Senate Majority Leader Mitch McConnell, R-Ky., who he has quarreled often with in the past.

“We don’t have the votes in the Republican conference,” said Cruz. “I don’t know if we even have half of Republicans who would support changing the filibuster.”

That hasn’t stopped Cruz from pushing other ideas unpopular with his party, and he points to some success.

During tax negotiations last October, Cruz said he personally pitched the idea of stripping Obamacare’s individual mandate through the tax bill. Fresh off a string of embarrassing failures in their attempts to repeal the law, Cruz said party leaders didn’t want to “muck up tax reform by getting back into” health care.

“Last October I began pitching [it]… It was me and a half-dozen conservatives,” said Cruz. “Most of the conference was skeptical… We began making the case both privately within the conference and publicly to the American people.”

All Republican senators later voted to include the measure, which Cruz called “one of the major victories in tax reform.”

Cruz is one of just two Senate Republicans facing a serious challenge from a Democrat in 2018, along with Sen. Dean Heller, R-Nevada. Republicans are defending just eight of the Senate seats up for re-election. Democrats are defending 24 seats, as well as two independents who caucus with them.

Cruz was elected to the Senate in an upset primary victory in 2012, then went on to finished second in the GOP presidential primary four years later. He avoided a major challenge from his own party in his first re-election race to the Senate. Texas’s primary will be held March 6.