A second House Republican will back a bill that calls for an independent commission to probe the Russian government's interference in the 2016 presidential election and possible collusion with Donald Trump's campaign, the measure's chief sponsor says.

Rep. Eric Swalwell of California tells U.S. News his Republican counterpart, Rep. Justin Amash of Michigan, is signing on to Democratic legislation that would create a 12-member bipartisan commission to examine Russia's attempts to undermine the U.S. electoral process, similar to the panel established following the Sept. 11 terror attacks.

Swalwell originally introduced the legislation in December, and this session's version has accumulated the support of every member of the Democratic caucus. Rep. Walter Jones of North Carolina had been the sole Republican to back the commission.

Amash's support is significant because he's known as one of the most conservative lawmakers in the Republican caucus, as well as one of Trump's most consistent critics.

On Tuesday, Amash called Trump's assertion in his letter to FBI Director James Comey that Comey had told him he was not under investigation "bizarre," and signaled potential support for an independent commission.

He's also previously called out the Trump administration for its consideration of curtailing press freedoms, and compared Trump to a fifth-grader after the president targeted members of the House Freedom Caucus over the initial defeat of the White House-backed Obamacare replacement.

In an interview with U.S. News on Thursday, Swalwell, a member of the House intelligence committee, said he knows of at least four other Republicans who are contemplating signing on to the legislation to create an independent commission. The method and timing of Trump's firing of Comey only heightened their interest, he said.

"I've been talking to them for six months about it, making an ongoing case for them to join. They're open-minded to it," Swalwell says.

The creation of an independent commission still would face steep hurdles given GOP majorities in both chambers of Congress and limited Republican calls for some type of special Russia probe even after Comey's dismissal.

But Swalwell says even small gains will be significant, especially as more information continues to come to light in regard to Comey's firing and whether it was connected to what investigators were finding in the FBI's ongoing Russian investigation.