President Trump, in a Cabinet meeting on the 12th day of a partial government shutdown that has no end in sight, said he'll keep the government shutdown "as long as it takes."

Mr. Trump, in a session with the Cabinet and reporters that lasted nearly two hours, gave few details on how he hopes to end the shutdown that has hundreds of thousands of federal employees furloughed or working without pay. Mr. Trump is demanding billions for his border wall.

"As long as it takes," Mr. Trump said. "I mean look. I'm prepared – I think the people of the country think I'm right. I think the people of this country think I'm right. Again. I could've done nothing. I could've had a lot easier presidency by doing nothing. But I'm here, I want to do it right. But I'm not only talking here. I'm talking about Middle East problems, and other problems and North Korea problems."

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Mr. Trump told his Cabinet he thinks they can work with Democrats on border security, calling the border wall like a sieve and emphasizing the need for a wall. Mr Trump wouldn't say if he is open to taking less than the $5 billion he wants to build the border wall, but dismissed the $2.5 billion floated by his own vice president.

"No, not $2.5, no," Mr. Trump said. "We're asking for 5.6. And somebody said 2.5. No, look, this is national security we're talking about. You know just like we talk about the military, just like we're talking about Syria or Afghanistan or all these different places."

Mr. Trump also claimed he essentially "fired" former Secretary of Defense James Mattis. That's after the White House repeatedly insisted Mattis retired. Mattis' resignation letter was intensely critical of the president's military approach, and Mattis said the president deserves a defense secretary who views the world like he does.

Mr. Trump questioned what Mattis did for him.

"But what's he done for me?" Mr. Trump asked. "How has he done in Afghanistan? How has he done in Afghanistan? Not too good. Not too good. I'm not happy with what he has done in Afghanistan, and I shouldn't be happy. But he was very and very thankful when I got him $700 billion. And the following year $716 billion. So I mean I wish him well. I hope he does well. But as you know President Obama fired him and essentially so did I. I want results."

The president also aired his grievances about troop withdrawals in the Middle East, the border wall, and incoming Sen. Mitt Romney, who wrote an op-ed criticizing the president Tuesday night. Mr. Trump said he was "surprised" at Romney's op-ed, but hopes he's a "team player."

"So I was surprised for Mitt Romney but i just hope he's going to be a team player, and if he's a team player, uh, that'll be great," Mr. Trump said. "I will say this, if he fought really hard against President Obama like he does against me, he would have won the election. Does that make sense to you? If he fought the way he fights me, I'm telling you he would have won the election. But I think he's going to end up being a team player, I think he agrees with many of the things that we've done and many of the things that we have in mind and we'll see what happens."

Later in the day, Mr. Trump will meet with top Republicans and top Democrats in a closed-press Situation Room meeting on border security and the shutdown. Mr. Trump is demanding funding for his border wall, funding Democrats say they won't give him. That meeting is set for 3 p.m. The dynamics in Washington are shifting quickly, with Democrats taking control of the House officially on Thursday.

Earlier, the president lashed out at Romney on Twitter over the scathing op-ed that claimed the president has failed to live up to the mantle of his office and has weakened America on the world stage.

"Here we go with Mitt Romney, but so fast! Question will be, is he a Flake? I hope not. Would much prefer that Mitt focus on Border Security and so many other things where he can be helpful. I won big, and he didn't. He should be happy for all Republicans. Be a TEAM player & WIN!" the president tweeted Wednesday.