FILE PHOTO: U.S. Sen. Tom Udall (D-NM), visits with Phyliss Young, an organizer of the tribal get-out-the-vote coalition ahead of the 2018 mid-term elections on the Standing Rock Reservation in Fort Yates, North Dakota, U.S. October 26, 2018. Picture taken October 26, 2018. REUTERS/Dan Koeck

WASHINGTON (Reuters) - Democratic Senator Tom Udall on Monday announced that he will not seek re-election in 2020, ending a long career of representing the state of New Mexico in the U.S. Congress.

“The worst thing anyone in public office can do is believe the office belongs to them, rather than to the people they represent. That’s why I’m announcing today that I won’t be seeking re-election next year,” Udall, 70, said in a statement.

Udall, a member of the Senate’s Foreign Relations and Appropriations committees, has served in the chamber since 2009 and before that was in the House of Representatives for a decade. His uncle, Morris Udall, was a prominent member of the House of Representatives who ran unsuccessfully for president in 1976.

Democrats are hoping to capture majority control of the Senate in the November 2020 elections. Republicans hold 53 seats, Democrats have 45 and two independents align themselves with the Democrats.

Republicans will be defending 21 of their seats next year, while Democrats will have 12 up for grabs.

So far, two Republicans, Lamar Alexander of Tennessee and Pat Roberts of Kansas, have announced their retirements.

Democrats are thought to have a strong chance of holding Udall’s seat in New Mexico.

In his announcement, Udall said “there will be more chapters in my public service,” but he did say whether he plans to run for another elective office.