Washington (CNN) Bernie Sanders said Senate Democratic leaders discussed Monday whether the party would flatly oppose any nomination President-elect Donald Trump makes to the Supreme Court.

At the same time, Sanders urged fellow Democrats against simply obstructing the incoming administration -- demonstrating the difficulty progressives are having in deciding how to handle the incoming president.

Speaking at a town hall in Washington sponsored by CNN and moderated by Chris Cuomo, Sanders blasted Republicans for acting "shamefully and outrageously" by refusing to consider President Barack Obama's nomination of Merrick Garland to the Supreme Court last year. He suggested Democrats may not "do the right thing" and instead adopt the GOP's tactics.

Meanwhile, Sanders, a Vermont senator and progressive favorite in the 2016 Democratic primary, acknowledged Obamacare has "problems."

"But we damn well aren't going to see it repealed and have no replacement there at all," he said.

And he drew another clear line with Trump, saying: "I will tell you this: He ran a campaign whose cornerstone was bigotry. It was based on sexism, on racism, on xenophobia, and on that issue, I will not compromise."

Still, Sanders said he hopes Democrats don't use the "obstruct, obstruct, obstruct" tactics against Trump that congressional Republicans deployed against Obama.

"I don't think that's what we do," Sanders said. "I think where Trump has ideas that make sense that we can work with him on, I think we should."

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Sanders wouldn't say whether he would again seek the presidency in 2020. But said there's one issue on which he would work with Trump: trade. Both railed against the North American Free Trade Agreement on the campaign trail and said they opposed the Trans-Pacific Partnership.

"I believe we need a new trade policy. I believe we tell corporate America they've got to control their greed," Sanders said. "Mr. Trump is prepared to sit down and work on a new trade policy which is based on fairness, not just on corporate greed, yes, I will be happy to work with him."

Progressives prepare to fight

With Hillary Clinton defeated and Obama counting down his final days in office, Democrats are increasingly reliant on Sanders, Massachusetts Sen. Elizabeth Warren and other leading progressives to set the party's message -- and pick its battles. Democrats face this challenge as they're poised to lose all their levers of power in Washington.

Changes to Senate rules made when the party had the majority now mean its members can't block any of Trump's Cabinet nominees. Nor can Democrats stop the GOP push to repeal Obamacare using the same filibuster-avoiding budget rules Obama used to push the health reform law through Congress.

The party is also down to 17 of the nation's 50 governor's offices, and Republicans have full control of the legislatures in 32 states -- realities that make it harder for Democrats to stop changes to voting access laws that have hurt the party.

Sanders said Democrats have lost support among working-class voters in part because the party joined Republicans in deregulating Wall Street and enacting massive trade deals. Doing that, and then claiming the mantle of the middle class, won't work, he said.

"They're not going to believe you," he said of voters. "What we have got to do is come up with an agenda that speaks to the needs of the working people."

It's against that backdrop that Democrats will begin to fight back this week as they seek to make the case that Trump is selling out his working class base by tapping corporate figures such as ExxonMobil CEO Rex Tillerson for secretary of state, Goldman Sachs veteran Steve Mnuchin for treasury secretary and fast food executive Andy Puzder for labor secretary.

Sanders said he has real concerns about two of Trump's nominees -- Alabama Sen. Jeff Sessions for attorney general and Oklahoma Attorney General Scott Pruitt for EPA administrator. The Vermont senator said he wants to hear what they have to say before deciding whether he'll vote against them -- but acknowledged he's not inclined to vote for either of them.

"All that I am doing here is trying to be polite," Sanders said.

Heated moment

A heated moment unfolded when a Trump-supporting small business owner pressed Sanders on what he said were a raft of burdensome Obama administration regulations.

Sanders pushed back, telling the man: "Obama did raise taxes on the top 1 or 2%, and you know what? I would have gone further. I think the wealthiest people in this country are doing phenomenally well."

The questioner continued to press Sanders, who wouldn't give an inch. "The devil is in the details. We've got to see what those regulations are," he said, adding that he wouldn't rule out reconsidering some regulations, but saying he didn't know which ones the man was citing.

"It's very easy to blame Barack Obama for everything, by the way. Some of those regulations may be state, may be local," Sanders said.

"But some of them, if you're talking about -- you now, you have some folks out there who really want the freedom to pollute our air and pollute our water," he said. "They want to get rid of those regulations. I don't agree. I don't agree. We have got to protect our environment."