A mere two days after the longest government shutdown in U.S. history ended, the White House is making clear that President Donald Trump is ready to do it all over again if he doesn’t get funding for a border wall. “Yeah, actually I think he is,” acting White House Chief of Staff Mick Mulvaney said on CBS’ Face the Nation when he was asked if the president is willing to shut the government down again. “He is willing to do whatever it takes to secure the border. He does take this very seriously. This is a serious humanitarian and security crisis.” Mulvaney did say that Trump “doesn’t want to shut the government down” and expressed optimism that the “negotiations are far from over.”

Trump himself appeared to try to lay some pressure on Democrats by sending a series of tweets that pushed the need for a border wall. “BUILD A WALL & CRIME WILL FALL!” he tweeted. Trump also retweeted a portion of an interview with counselor Kellyanne Conway that mentions the threat of heroin coming through the southern border.

BUILD A WALL & CRIME WILL FALL! pic.twitter.com/yDdCG5DCxn — Donald J. Trump (@realDonaldTrump) January 27, 2019

“300 people are dying from heroin overdoses a week in this country, 90% of it is coming over the southern border… We’ve got to stop it.”—@KellyannePolls pic.twitter.com/h4E5TyV8Wb — GOP (@GOP) January 26, 2019

Trump also tried to make an economic argument for combating illegal immigration. “We are not even into February and the cost of illegal immigration so far this year is $18,959,495,168. Cost Friday was $603,331,392. There are at least 25,772,342 illegal aliens, not the 11,000,000 that have been reported for years, in our Country. So ridiculous! DHS,” Trump wrote. Although he signs off the tweet with “Department of Homeland Security,” he didn’t cite a source for the numbers. Analysts have characterized Trump’s estimates of the cost of undocumented immigrants as absurd.

We are not even into February and the cost of illegal immigration so far this year is $18,959,495,168. Cost Friday was $603,331,392. There are at least 25,772,342 illegal aliens, not the 11,000,000 that have been reported for years, in our Country. So ridiculous! DHS — Donald J. Trump (@realDonaldTrump) January 27, 2019

Mulvaney acknowledged he didn’t know where the president got the figures, but emphasized that what is important is the overall message. “I’m not exactly sure where the president got that number this morning, but I think what you see him trying to do is point out how silly this debate is,” Mulvaney said. “This is not that much money in the greater scheme of things.” He also defended the president’s claim that that the number of undocumented immigrants in the country is larger than 11 million. “We know that it’s going up because we know, for example, that 60,000 new illegals are coming across each month for the last three months. Again, a number that is not made up,” Mulvaney said. “That is a real number. So we know the number has to be larger than 11 million. I’ve seen ranges as high, I think, of 30 or 40 million.”