Sen. Jon Tester Jonathan (Jon) TesterPence seeks to boost Daines in critical Montana Senate race This World Suicide Prevention Day, let's recommit to protecting the lives of our veterans Filibuster fight looms if Democrats retake Senate MORE (D-Mont.) said Thursday that he is open to repealing and replacing ObamaCare even as his party's leadership demands that Republicans drop their effort to nix former President Barack Obama Barack Hussein ObamaGOP senator blocks Schumer resolution aimed at Biden probe as tensions run high D-Day for Trump: September 29 Obama says making a voting plan is part of 'how to quarantine successfully' MORE's signature healthcare law.

"It needs to be improved. It hasn't been improved. We can either work to improve that or repeal it and replace it with something better. I'm open to either one," Tester, who is up for reelection in a state won by President Trump, told Fox News.

Tester doesn't support a House GOP bill that passed on Thursday, but also said he doesn't think lawmakers have done enough to try to fix the Affordable Care Act since it was passed in 2010.

"There were plenty of mistakes made with the [Affordable Care Act], there's no doubt about that," he said. "Quite frankly, we didn't make the modifications over the last six, seven years, for obvious reasons, to make that bill better."