Rep. Joe Kennedy III (D-MA) announced Monday that he is considering a U.S. Senate bid in Massachusetts, increasing the likelihood that he would face off in the Democratic primary against incumbent Sen. Ed Markey (D-MA).

“Over the past few weeks I’ve begun to consider a run for the U.S. Senate. This isn’t a decision I’m approaching lightly and— to be completely candid— I wasn’t expecting to share my thoughts so soon,” Kennedy said in a Monday Facebook post to supporters.

Kennedy’s potential candidacy is also official. He filed paperwork with the Federal Election Commission (FEC) on Monday so he could start fundraising for his Senate bid.

Kennedy, who delivered the Democrats’ response to the State of the Union in 2018 and is on his fourth term in Congress, is considered to be a rising star in the Democrat Party and could pose a challenge to both Senate incumbents in Massachusetts.

Markey is up for re-election in 2020, and Sen. Elizabeth Warren (D-MA) is running for president, meaning her seat would open up should she win the presidency. Warren’s next re-election to the Senate is in 2024.

Kennedy comes from a long line of politicians in the family, including former President John F. Kennedy, Attorney General Robert F. Kennedy, and former Sen. Ted Kennedy (D-MA).