President Donald Trump has made it known that he’s proud of the U.S. employment picture, but if the government shuts down for an extended period of time, those numbers could take a hit.

On Thursday, Kevin Hassett, chairman of the Council of Economic Advisers, told CNBC, “Economically it is not something that really has a big long-run effect, but for sure if we had a long government shutdown then it might show up in the jobs report.”

The White House didn’t immediately respond to a request for clarification on the time frame of a “long” shutdown.

But on Friday morning, Trump himself warned of “a shutdown that will last for a very long time” if the Senate didn’t back a spending bill that includes funding for a southern border wall.

The Democrats, whose votes we need in the Senate, will probably vote against Border Security and the Wall even though they know it is DESPERATELY NEEDED. If the Dems vote no, there will be a shutdown that will last for a very long time. People don’t want Open Borders and Crime! — Donald J. Trump (@realDonaldTrump) December 21, 2018

Unemployment is at its lowest level since 1969 and wage growth is up. In October, job growth blew past expectations. However, in November, that growth fell short of expectations amid fears that the economic expansion is slowing down.

Chances of a partial government shutdown increased earlier in the day when House Speaker Paul Ryan said Trump will not sign a Senate-passed sending bill.

The legislation, unanimously approved by the Senate on Wednesday night, funds the government through Feb. 8. It was expected to pass through the House with the president’s support.

However, Trump, who wants $5 billion to build a border wall between the U.S. and Mexico, will refuse to sign it without the border security protections he wants, Ryan said.

Hassett said the president has a very firm position on the matter.

“The president has a very small ask that he’s had really since he arrived that Congress focus, like voters want him to do, on border security,” Hassett said on “Closing Bell. ” “He’s absolutely adamant that’s going to happen.”

Hassett expects a “down to the wire” negotiation process.

— CNBC’s Jacob Pramuk and Kevin Breuninger contributed to this report.