Attorney General William Barr on Wednesday continued his tepid defense of the Trump administration’s decision not to defend Obamacare and, instead, to side with 21 conservative states mounting an effort to tear down the landmark health care law covering millions of Americans.

“The attorney general should be able to advance positions that he believes are defensible and reasonable legal positions, even if they are not positions that the attorney general would adopt if the attorney general was a judge deciding the case,” Barr told lawmakers at a Senate Appropriations subcommittee hearing.

When a federal appeals court judge ruled two weeks ago that Trump-era legislation and other recent actions meant the entire Affordable Care Act should be overturned, the Justice Department decided to reverse itself and support the ruling -- rather than appeal using the same argument it had used previously.

That DOJ decision is opposed by a bipartisan group in the Senate, so much so that the Majority Leader, Mitch McConnell of Kentucky, recently told the president that the chamber would not be accommodating Trump’s desire to revisit the Affordable Care Act this year ahead of the crucial 2020 elections. It was a decision that essentially forced Trump to delay his plans to try to repeal and replace the legislation until next year.

“I disagree strongly with the department’s decision not to defend the ACA,” Sen. Susan Collins, R-Maine, told Barr at the hearing, noting that the ACA has a severability clause that enables pieces of it to be removed without the entire law falling.

And though the attorney general was reportedly opposed to the idea of reversing course on Obamacare at first, he then expounded on his reasoning for eventually deciding that his department would step back from defending the law, doing so in a way that drew more questions.

Barr referenced the 2012 Supreme Court ruling upholding the so-called individual mandate requiring Americans to buy health insurance or pay a penalty. The court ruled 5-4, with Chief Justice John Roberts siding with the majority, that the mandate was unconstitutional under the Constitution's Commerce Clause but that it could stay as part of Congress' constitutional power to tax Americans.

“I’m really surprised … because the Supreme Court did uphold the law - the ACA - and now the attorney general is saying we will not defend it, regardless,” Sen. Dianne Feinstein, D-Calif., scoffed. “It seems to me that that’s a problem. Something that's duly passed and upheld as legal, that the attorney general has a duty to defend it.”

But Congress last year struck down the law's mandate when it approved tax cut legislation, and that appeared to be a pivotal move to Barr.

“Well, the law was originally upheld because the mandate was held as a tax. Justice Roberts’ opinion said it can be upheld as a tax even though it couldn't otherwise be upheld,” Barr said, calling the mandate “unconstitutional in my opinion,” and adding, “But for finding it a tax you would have had five votes against it. Once the penalty was removed -- the financial penalty was removed -- that provision could no longer be justified as a tax which means that it would have to fall.”

“At the end of the day I felt that this was a defensible legal position to take,” Barr reasoned.

“This struck me like lightning that one person decide - I assume the president wants you to - made this decision and everything that was done by way of proper legislative action has been taken and signature of a president, I just don't ever recall anything like this happening in the past quarter of a century,” Sen. Feinstein said.

Barr did leave open the question that Congress may have actually intended Obamacare to remain in place, precisely because it has never been able to repeal that law or strip out any other provisions in it.

“I know there's an additional point there, which is the fact that Congress did take out the penalty from the mandate and, therefore, should that act be viewed as essentially validating the rest of this statute.

“I would just make the point that Congress had the opportunity to strike other provisions, and it chose not to,” Sen. Collins said.

Sen. Joe Manchin, a West Virginia Democrat, told Barr that the administration’s current position has hindered Congress’ ability to make changes to Obamacare.

And the senator asked, “Are you going to be in a position to defend the law” now that DOJ is against it?

Barr, without hesitation, said, “Yea, yes, senator.”