(CNN) Freshman Democratic Rep. Rashida Tlaib is pushing ahead with her impeachment resolution — bucking the leadership of her own party again and working to gather support ahead of plans to formally introduce the proposal this week.

Tlaib is circulating a letter among her colleagues that directs the House Judiciary Committee "to inquire whether President Trump committed impeachable offenses."

"We all swore to protect our nation, and that begins with making sure that no one, including the President of the United States, is acting above the law. I urge your support in recommending that the House Committee on Judiciary begin hearings, take depositions, and issue subpoenas to answer this question that is fundamental to the rule of law and the preservation of our democracy," the letter says.

Tlaib's letter appears to put her on a collision course with some rank-and-file members of her party as well as Democratic leadership, who appear interested in moving on to other fights following the conclusion of special counsel Robert Mueller's investigation.

Tlaib also spoke briefly in Tuesday morning's caucus meeting, where she asked about the next steps of the investigation and mentioned her impeachment resolution, but there was no discussion of it specifically by other members.

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