President Trump signed the criminal justice reform bill he and son-in-law and senior adviser Jared Kushner lobbied for, marking a significant bipartisan achievement in a time when successful bipartisan legislation on major issues is rare.

Mr. Trump signed the criminal justice reform bill in the Oval Office, after the House and Senate easily passed the legislation, with 12 Republican senators voting against the bill and all Democratic senators present voting for it. The legislation gives judges more discretion when sentencing some drug and lower-level offenders, and increases prisoner rehabilitation efforts.

Mr. Trump called the passage of the criminal justice bill in the Senate to be a "tremendous evening for the Republicans." Sen. Ted Cruz also spoke, praising Republican Sen. Mike Lee, a co-sponsor of the bipartisan bill.

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"Mike bled for this bill," Cruz said.

But that accomplishment is being quickly overshadowed, with hours to go until a government shutdown that Mr. Trump says will last a "very long time" if the Senate doesn't approve a short-term spending bill that includes $5 billion in funding for his border wall. The president is urging Senate Majority Leader Mitch McConnell to use the "nuclear option" to lower the threshold for votes needed in the Senate from 60 to a simple majority, something McConnell has refused repeatedly to do because he knows Democrats could gain control of the Senate again in the future.

"It's totally up to the Democrats as to whether or not" there is a shutdown, Mr. Trump said during the bill signing. "We are going to be working very hard to get something passed in the Senate," he added. He also said that he was "totally prepared for a really long shutdown."

Although Mr. Trump previously said he was "willing to take the mantle" for the shutdown, he is now blaming congressional Democrats if one occurs.

"There's a very good chance it won't get passed. It's up to the Democrats. So it's really, the Democrat shutdown, because we've done our thing," Mr. Trump said.

On top of that, news that Secretary of Defense James Mattis is stepping down, amid planned U.S. drawdowns in Syria and Afghanistan, raised concerns from even the president's closest allies about where the nation's national security is headed. Mattis, in his resignation letter said that the president should have a defense secretary who more aligns with his views.