Jay Clayton, President Trump’s nominee to lead the nation’s intelligence community, will face questions today from lawmakers amid a new push by the White House to use declassified intelligence reports to highlight concerns about election security.

Ahead of a Thursday speech by Mr. Trump, the current acting director of national intelligence, Bill Pulte, has been working on the declassification and potential release of documents related to election security or interference.

At a Senate hearing beginning at 9:30 a.m. local time, lawmakers are likely to press Mr. Clayton, currently the U.S. attorney for the Southern District of New York, on that effort, as well as on comments he has made about potential election fraud in California.

Last month, Mr. Clayton was poised to have a relatively easy path to confirmation. Senate Democrats and Republicans were intent on preventing Mr. Pulte, a close ally of Mr. Trump with no national security experience, from becoming the acting director. They were preparing to quickly hold a hearing and then suspend Senate rules to secure a vote on the Senate floor to confirm Mr. Clayton to the post.

But Mr. Trump abruptly delayed the confirmation proceedings, ordering Mr. Clayton not to appear at the initial hearing, a move that allowed Mr. Pulte to take over from Tulsi Gabbard in the position of acting director.

The decision to delay Mr. Clayton’s hearing also prompted Senate Democrats to pull their support for a bill authorizing a powerful national security surveillance program.

Mr. Trump’s machinations over the Office of the Director of National Intelligence have increased the concerns of Senate Democrats about any nominee for the office, and Mr. Clayton is likely to face tough questioning.

Neither Mr. Pulte nor the White House has released declassified intelligence documents related to elections, and Mr. Clayton is likely to try to avoid answering specific questions before Mr. Trump’s speech on Thursday.

But he will likely be pressed more broadly on election issues and on politicized intelligence.

According to excerpts from his remarks, Senator Mark Warner of Virginia, the senior Democrat on the Intelligence Committee, is set to raise concerns with Mr. Clayton about “repeated attempts by this administration to politicize” America’s spy agencies.

“Recent reports suggest that the IC’s annual analytic objectivity survey shows a substantial increase in the number of IC employees who say they are concerned about intelligence analysis being undermined by political influence,” Mr. Warner is set to say, referring to the intelligence community. “I hope that, should you be confirmed, you will make it clear that this kind of politicization has no place in the intelligence community.”

While Mr. Clayton’s nomination has been endorsed by some Democrats, there could be some questions related to his oversight of the U.S. attorney’s office.

Last week, Mr. Clayton authorized subpoenas for a group of New York Times reporters who had reported on security issues relating to the new version of Air Force One that had been donated to the United States by Qatar.