Sen. Mark R. Warner (D-Va.) on Capitol Hill in February. (Kevin Lamarque/Reuters)

The Senate Intelligence Committee’s top Democrat is filing legislation that seeks to impose criminal penalties on political campaign officials who fail to disclose contacts with foreign nationals, as President Trump’s staff did ahead of the 2016 election.

Sen. Mark R. Warner (D-Va.) said he was inspired by the “at least 140 contacts between Trump associates and Russian nationals or WikiLeaks” identified by special counsel Robert S. Mueller III. The legislation would impose fines of up to $500,000 and sentences of up to five years in prison on campaign officials who in the future do not report outreach from foreign nationals within one week.

“Most Americans already know that if a foreign adversary reaches out about interfering in our elections, you should report that contact,” Warner said in a statement. “It’s clear that some Americans haven’t taken that responsibility seriously — in fact, the Trump campaign welcomed the help.”

Warner is vice chairman of the Intelligence Committee, which for more than two years has conducted Congress’s only bipartisan investigation into Russian interference in the 2016 presidential election. His legislation does not have Republican co-sponsors — a reminder of how politically tricky the task of turning investigative findings into policy changes will be.

Warner characterized his bill as an effort to expose when foreign nationals attempt “to coordinate or collaborate” during a political campaign — something Trump and his allies have strenuously denied the president engaged in, seeking to bolster their case by pointing to Mueller’s decision not to file criminal charges.

Despite those denials, certain contacts between the Trump campaign and foreign nationals — such as former Trump campaign chairman Paul Manafort’s ties to a Russian oligarch and a 2016 meeting in Trump Tower — have drawn scrutiny from Democrats and Republicans perplexed by the nature of those contacts and why the campaign did not regard them as suspect.

“Paul Manafort . . . he is on the payroll of a Russian oligarch that has interests completely disaligned with the American people,” Sen. Ben Sasse (R-Neb.) said this month in a hearing with Attorney General William P. Barr about the Mueller report. “Could we have campaign chairmen and women running around the U.S., U.S. citizens who have U.S. campaign talent and experience, paid for by foreign entities, just choosing to volunteer on campaigns going forward? Is that legal?”

Even on the relatively bipartisan Intelligence Committee, parsing such matters often splits along party lines. Chairman Richard Burr (R-N.C.) and Warner have publicly disagreed over whether they have seen evidence of collusion arise during their inquiry. In a recent interview, Burr also stressed that if the panel was going to scrutinize questionable foreign contacts on the part of the Trump campaign, it would have to do so in equal measure for Hillary Clinton’s campaign.

“If you’re going to be critical of the willingness of the Trump campaign to sit with a Russian who probably said, ‘Hey, we got dirt on Hillary Clinton’ . . . you’ve got to be critical of the Clinton campaign hiring a lawyer to pay Glenn Simpson to hire a retired British agent to create a dossier from Russian contacts,” he said, referring to the figures behind a dossier alleging the president had personal and financial ties to Russian officials.

Though the Intelligence Committee has not completed its investigation, certain election security proposals have emerged. Thus far Congress has approved extra funding for state and local entities to improve the security of their election systems, and a bipartisan group of senators has backed measures to declare election interference illegal and deny U.S. visas to those who engage in it. Most Democrats, but few Republicans, have also endorsed a measure to require better disclosure of the funders behind online political advertisements.

Warner’s foreign-contacts bill would institute a requirement that campaigns set up a compliance system certified by the candidates themselves, in addition to imposing foreign penalties. It also requires that all incoming workers be trained about their obligation to report foreign attempts to donate information, services or funds or “otherwise coordinate with the candidate.”

The campaign would be required to report such contacts to the Federal Election Commission, which would in turn notify the FBI. Campaigns would be required to keep records of all such contacts for three years.