WASHINGTON — As Republicans wrangle over how to advance their Affordable Care Act overhaul, Sen. Pat Toomey has emerged as a key voice arguing for conservative priorities.

For weeks, the Pennsylvania Republican has pushed a plan to rein in Medicaid spending, urging the Senate to go even further than the bill approved by House Republicans — and putting him at odds with GOP senators and governors from other states that, like Pennsylvania, have expanded Medicaid.

Another clash came Thursday when Toomey argued against a centrist proposal to retain one of the Obamacare taxes. GOP moderates argued that keeping the tax on wealthier people's investment income would allow them to direct more money to helping the needy obtain health coverage.

"It's a bad idea," Toomey said as he left a GOP strategy session.

The senator instead joined conservatives who want to repeal all the taxes in the law, saying they destroy jobs.

As one of the senators who helped craft the bill, one of its most vocal public defenders, and a leading GOP voice on fiscal matters, Toomey has been swarmed by reporters for weeks, and was sought out again Thursday as Republicans tried to negotiate their way to the 50 votes needed to advance their stalled bill.

The longtime budget hawk, who squeaked to reelection last year by touting his more moderate credentials, but who has consistently railed against former President Barack Obama's health law, appeared on Fox News and CNN to speak up for the GOP approach, and was on CBS over the weekend.

Republican senators are being pulled between conservatives, who want to go further in erasing the health law, and moderates who want to soften the bill and counter the attack that they are cutting taxes for the wealthy while slashing health care for the poor.

"It's not an acceptable proposition to have a bill that increases the burden on lower-income citizens and lessens the burden on wealthy citizens," said Sen. Bob Corker (R., Tenn.), as reported by Politico.

So some Senate Republicans called for leaving in place a 3.8 percent tax on investment income, levied on individuals who make more than $200,000 a year and couples making more than $250,000. It's expected to raise $172 billion over the next decade. Keeping the tax might leave more money for health programs or aid to help people obtain insurance.

Toomey opposed that idea, and has also urged for technical changes that would lead to more steep cuts in projected spending on Medicaid, the program that, under Obamacare, has helped more than 700,000 Pennsylvanians obtain health coverage.

He argued that Medicaid is growing too fast and that spending has to be reined in to make the program sustainable for the long term. Democrats and Republicans from states such as Ohio, West Virginia, and New Hampshire have warned that the billions of dollars in reductions would force states like theirs — and Pennsylvania — to slash the program and cut coverage. Toomey argued that states can keep people on the program if they're willing to come up with more funding, much as they do for other aspects of Medicaid.

A number of Republican senators and governors have also argued that the Medicaid cuts could make it harder for people to obtain treatment for opioid addiction, and have sought billions in added money for that cause.

Toomey downplayed the idea that the GOP bill would hamper substance-abuse treatment — "I don't think that's actually the case," he said — but signaled that he was open to adding money to address the issue, which has ravaged Pennsylvania.

"I think in the end we're going to see an extraordinary effort to deal with addiction, especially opioid problems," he said.