WASHINGTON — The scope of congressional investigations into Russian meddling in the 2016 presidential contest came into sharper focus Wednesday as lawmakers said they intended to question the former chairman of the Trump campaign and to determine whether Russian social media “trolls” were connected to Trump’s election efforts.

The Senate Judiciary Committee plans to question former campaign chairman Paul Manafort and will subpoena him if necessary, said the panel’s Republican chairman, Sen. Chuck Grassley of Iowa. Grassley said he and the committee’s top Democrat, Dianne Feinstein of California, have agreed to try to bring Manafort before the panel for questioning about the government’s enforcement of a law requiring registration of foreign lobbyists. Feinstein’s office confirmed that they plan to question him.

Manafort would certainly also be asked about his participation in a Trump Tower meeting last summer with President Trump’s eldest son and his son-in-law, where the purpose was to hear potentially damaging information about Hillary Clinton from a Russian lawyer.

Manafort disclosed the meeting in a package of information he provided to the Senate and House intelligence committees, who have been investigating potential coordination between Russia and the Trump campaign, as is Robert Mueller, the former FBI director appointed by the Justice Department as the special counsel.

“Obviously it would be appropriate for anybody to get into anything that went on at that meeting, and he was at that meeting,” Grassley told Iowa reporters.

A person close to Manafort said he hasn’t received a letter from the Senate Judiciary Committee about a possible interview. The person spoke on condition of anonymity to discuss Manafort’s private interactions with the committee.

Separately, Rep. Adam Schiff, the top Democrat on the House Intelligence Committee, said his panel wants to look at the use of Russian social media “trolls” and whether they were connected to the Trump election campaign, as part of a broader committee investigation into Russian election meddling. Trump’s son-in-law, Jared Kushner, oversaw digital strategy for the campaign.

The lawmakers spoke one day after Trump Jr. disclosed on Twitter a series of emails that revealed his eagerness to hear negative material on Clinton from the Russian lawyer.

The exchange showed Trump Jr. conversing with a music publicist who wanted him to meet with a “Russian government attorney” who supposedly had dirt on Clinton as “part of Russia and its government’s support for Mr. Trump.” He was told the Russian government had information that could “incriminate” Clinton and her dealings with Russia.

“I love it,” Trump Jr. said in one email response.

In an interview before departing Wednesday evening for France, President Trump told Reuters that he didn’t know about the meeting “until a couple of days ago when I heard about this.”

The president’s attorney, Jay Sekulow, said in an interview with NBC’s “Today” that Trump Jr. did not violate any laws by accepting the meeting. He said the president had not been aware of Trump Jr.’s June 2016 meeting and didn’t find out about his son’s email exchange until “very recently.”