Rep. Joe Kennedy filed a statement of candidacy and a principal campaign committee for a 2020 U.S. Senate run on Monday. The move came less than two hours after the congressman posted on Facebook that he is considering a campaign against fellow Democrat Ed Markey, the incumbent.

Kennedy's office told CBS News that the congressman has still not made a decision on challenging Markey, and that the campaign committee was created to support Kennedy in his exploratory effort as he works towards a decision. So while Kennedy has not formally entered the race, the committee would allow him to fundraise and campaign like a candidate.

"I hear the folks who say I should wait my turn, but with due respect -- I'm not sure this is a moment for waiting," the 38-year-old Kennedy wrote in his Monday Facebook post.

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"Our system has been letting down a lot of people for a long time, and we can't fix it if we don't challenge it. I've got some ideas on how to do that. And I don't think our democratic process promises anyone a turn. What it does promise is the chance for anyone to earn it — if we think we have something to offer and are willing to put ourselves and our ideas out there."

A Kennedy run against Markey would set the stage for an expensive and high-profile primary in Massachusetts, one of the most Democratic states in the country.

Kennedy, who was elected to the House in 2012, is the grandson of Sen. Robert Kennedy and was chosen to give the official Democratic response to President Trump's State of the Union address last year. Markey, meanwhile, has been in Congress since 1976 and already has secured endorsements from Sen. Elizabeth Warren, Boston Mayor Marty Walsh, and the League of Conservation Voters.