The Republican National Committee paid to generate thousands of calls to the congressional offices of nearly three dozen House Democrats in recent weeks, an effort that was aimed at both shaping opinion around the impeachment inquiry and tying up the phone lines of the elected officials, according to two people briefed on the effort.

The calls were part of a broader effort by Republicans to influence public opinion around the investigation into President Trump. The Trump campaign and the Republican committee have taken the lead on political messaging defending Mr. Trump at a moment of political vulnerability, using television and digital ads, as well as the phone calls.

The fact that the calls to congressional offices, estimated to number 11,000, were partly intended to jam the phone lines of House Democrats — potentially thwarting access to government offices — was described at a recent dinner of more than a dozen Republican aides, advisers and elected officials, known as the “Off the Record” dinner. Officials with the Republican National Committee told others at the dinner about the calls, suggesting they were automated and indicating that the aim was to tie up the phones in Democratic offices, according to two people briefed on what was said.

Asked about the calls, Republican committee officials said they were not prerecorded “robocalls.” The officials said the committee used a vendor to survey voters. Those voters who said they opposed the impeachment inquiry were given the option of being connected to their congressional representative’s office, the officials said.

“Our supporters are incredibly fired up to help us fight this impeachment charade,” said Mike Reed, a spokesman for the committee. “Our ‘stop the madness’ campaign has helped hundreds of thousands of voters get the information they need to reach out to their Democrat representatives and tell them to drop the phony impeachment inquiry and get back to work for the American people.”

The campaign, which resumed after the Columbus Day congressional recess, included automated calls and text messages urging voters to call Democrats. There have also been call sheets handed out to attendees outside Mr. Trump’s campaign rallies, with a script urging lawmakers to “end this witch hunt.”

The history of using robocalls against a political adversary is fraught. One of the most famous instances was in 2002, when a telemarketing company was hired by the New Hampshire state Republican Party to jam phone lines of a Democratic get-out-the-vote effort.

Campaign finance lawyers were split on whether it was proper for the Republican committee to generate calls on impeachment to congressional offices. Some said that targeting Democratic lawmakers at their offices appeared to be an attempt to limit the ability of a government office to communicate. And they raised questions about whether targeting congressional offices would be considered an improper use of campaign resources by the Republican National Committee.

But others suggested that such work fell into the regular course of activity that is allowed.

“They can use campaign and R.N.C. funds for impeachment-related work, including legal and advocacy,” said Adav Noti, the chief of staff at the nonprofit Campaign Legal Center. He said it was different from what was typically done “only as a matter of degree,” but not “as a matter of kind from standard legal activity.”