Arizona Sen. Kyrsten Sinema is joining Republican senators in a bid to permanently ax a piece of President Obama’s signature health care law.

The freshman Arizona Democrat this week co-sponsored a bill to repeal the Affordable Care Act’s annual fee on insurance providers. The bill is also backed by GOP Sens. John Barrasso of Wyoming and Cory Gardner of Colorado.

“I’m proud to work across party lines to end this harmful tax and make healthcare (sic) more affordable for Arizonans,” Sinema said in a press release.

It’s one of several moves she’s made teaming up with Republicans since coming to Congress in 2013 that have drawn criticism from the left.

She and other critics of the tax argue that the higher costs to insurers will be passed on to consumers through higher premiums, taking a toll on families and small businesses. Proponents of the tax, meanwhile, argue that delaying or repealing that fee adds to the federal deficit by eliminating revenue built into the health care law.

This isn’t a new issue for Sinema. As a House lawmaker, she also backed legislation to delay the tax and to repeal it entirely. The health insurance tax has already been suspended for 2019.

The Obama health care law was a central issue in Sinema’s Senate race against Republican Martha McSally, who lost the race but was appointed to serve out the remainder of the late Sen. John McCain’s term.

Sinema said on the campaign trail that she wanted to tweak the law, but keep it in place.

“Just a really practical approach. Keep the stuff that’s good. Fix the stuff that’s not good,” Sinema told The Arizona Republic.

McSally, meanwhile, supported a GOP-led effort to repeal the Affordable Care Act when she was in the House.

Sinema’s office sent out a statement this week from R.J. Orr, executive vice president and partner at the Tempe-based company Bluemedia, supporting her Senate bill.

“Lowering health insurance costs for Arizona job creators and families must be a priority for our representatives in Congress,” Orr said. “We applaud Senator Sinema for making one of her first actions in the U.S. Senate to sponsor legislation that would provide Americans with permanent, long-term relief from the health insurance tax.”

Dan O’Neal, Arizona state coordinator of the Progressive Democrats of America, said he wasn’t surprised by Sinema’s bill. O’Neal, whose group supports single-payer healthcare said, “In fact, it’s probably totally in line with her move toward the right.”

O’Neal was also disappointed that Sinema broke ranks with Democrats this week to advance Republican-led legislation to increase military assistance to Israel and Jordan while imposing new sanctions on Syria. Democrats blocked movement on that bill as they sought to pressure Republicans to move legislation to fund the government and end the ongoing shutdown.

“She didn’t have to do it,” O’Neal said. “She could have voted along with the rest of the Democrats.”

“She’s gone from being a progressive leftist to a far moderate moving toward the right, and I’m very disappointed in her votes, even though she’s one of the smartest people in the room,” he said.