WASHINGTON >> President Donald Trump’s oldest son was expected to meet privately on Thursday with a Senate committee investigating Russian interference in the 2016 presidential election, several senators said.

Donald Trump Jr.’s appearance before the Senate Judiciary Committee would probably focus on a meeting he had with a Russian lawyer and others during the final stretches of last year’s campaign. Emails released in July show that Trump Jr. was told the session at Trump Tower in New York was part of a Russian government effort to aid his father, the Republican nominee.

Special counsel Robert Mueller is investigating that meeting, also attended by Trump’s son-in-law, Jared Kushner, and then-campaign chairman, Paul Manafort. A grand jury has heard testimony about it.

Trump Jr. has also agreed to appear in the coming weeks before the Senate Intelligence Committee, which is conducting its own investigation.

Separately, former President Barack Obama’s national security adviser, Susan Rice, was meeting today with the House Intelligence Committee, according to a person familiar with the interview. This person wasn’t authorized to discuss the committee’s confidential work and spoke on the condition of anonymity.

That committee has subpoenaed the Justice Department and the FBI for documents related to a dossier of salacious allegations involving Trump and possible ties to Russia.

As for Donald Trump Jr., some Democratic senators said they planned to attend his session though tradition dictates that senators cannot ask questions at such interviews conducted by committee staff.

Sens. Richard Durbin, D-Ill., and Richard Blumenthal, D-Conn., said they would be there. Sen. Chris Coons, D-Del., was considering it.

“I go in with an open mind,” Durbin said. “I want to hear his answers to questions — there are plenty of questions — about the involvement of the Trump corporation as well as the Trump campaign with the Russians and other foreigners, and I just want to hear what Mr. Trump has to say.”

Durbin said he would be “shocked” if questions weren’t asked about whether the elder Trump knew about the Trump Tower meeting.

“The critical part of his testimony will be following the financial dealing,” Blumenthal said. He said he also wants to find out what Trump Jr. may know about potential obstruction of justice, adding there may have been conversations between the two about the firing of FBI Director James Comey and other matters.

Blumenthal and Coons said the private interview is no substitute for a public hearing, which the committee chairman, Sen. Chuck Grassley, R-Iowa, has promised will happen.

“This meeting is far less important than his public testimony, under oath, before the American people,” Blumenthal said.

Grassley would not say today whether he would issue a subpoena for Trump Jr. if he refuses to testify publicly.

Meanwhile, the Justice Department is reviewing subpoenas from the House intelligence committee.

In a letter Friday that was obtained by the AP, the committee wrote that it had served subpoenas on Aug. 24 to the department and the FBI for documents related to the committee’s investigation of Russian meddling. The Justice Department and FBI had missed the original Sept. 1 deadline, so the committee extended the deadline to Sept. 14.

The letter was signed by the committee chairman, Rep. Devin Nunes, R-Calif., who stepped back from the Russia investigation this year after he was criticized for being too close to the White House. Rep. Mike Conaway, R-Texas, took over the leading role, but his name does not appear on the letter.

As chairman, Nunes retains subpoena power in the committee.

According to the letter, the original subpoenas requested any documents related to the dossier and sought information about whether the department was involved in its production.

If the documents are not produced, the committee is seeking to compel Attorney General Jeff Sessions, who has withdrawn from investigations examining connections between Trump and Russia, and newly installed FBI Director Christopher Wray to testify in an open hearing. The committee issued two additional subpoenas to Sessions and Wray on late Tuesday.

“Resort to compulsory process was necessary because of DOJ’s and FBI’s insufficient responsiveness to the committee’s numerous Russia-investigation related requests over the past several months,” the letter said.

If the committee is unable to obtain documents or testimony, Nunes wrote, the committee “expressly reserves its right to proceed with any and all available legal options,” including a House vote to hold Sessions and Wray in contempt.

The Justice Department confirmed it was reviewing the subpoenas but declined further comment.

The dossier attracted public attention in January when it was revealed that then-FBI Director James Comey had briefed Trump, soon before he was inaugurated as president, about claims from the documents that Russia had amassed compromising personal and financial allegations about him.

It’s unclear to what extent the allegations in the dossier have been corroborated or verified by the FBI because the bureau has not publicly discussed it.

Rep. Adam Schiff, the top Democrat on the Intelligence Committee, said Tuesday evening on MSNBC that the subpoenas were issued over the objections of Democrats. Schiff said Republicans are working harder to discredit those who compiled the dossier than to find out if the allegations in it are true. He said Republicans should be more focused on getting documents from the White House.

The subpoenas were first reported by the Washington Examiner.