Updated 4:12 p.m., 12/17/13
(CNN) - In an apparent major setback for House Democrats, longtime Rep. Jim Matheson of Utah announced Tuesday he will not seek re-election next year.
"I take the role of representative seriously and intend to conclude this chapter of my service to our state in the same way I have always approached my job," Matheson wrote in a posting on his Facebook page.
The seven-term House Democrat suggested his next chapter would involve his home state, adding "You can count on me to work hard, to solve problems, to achieve progress and to put Utah first. While at the end of 2014 my tenure in the House of Representatives will come to an end, my duty to our state and our country will undoubtedly continue."
Matheson narrowly won re-election last year, beating out Mia Love, an African American mayor of Saratoga Springs, by less than 800 votes. Love, who enjoyed the support of tea party activists and other grassroots conservatives, was featured prominently by the national party with a prime speaking slot at the 2012 GOP convention in Tampa. Love announced earlier this year that she would once again challenge Matheson for Utah's fourth congressional district.
"Congressman Matheson has served our state with passion and has been a dedicated public servant during his tenure in Congress. His announcement today does not change my campaign to represent the people of Utah's 4th congressional district," said Love in a statement.
A leading member of the group of fiscally conservative Democrats known as the "Blue Dogs," Matheson was one of a dwindling number of Democratic moderates left in the House and frequently broke with Democratic leaders. He opposed the Affordable Care Act in 2009 and voted against Nancy Pelosi to serve as the top Democratic leader in the House.
Rep. Greg Walden, chairman of the National Republican Congressional Committee, said that Matheson's retirement announcement is a warning signal for Democrats.
"It's telling that Matheson, who didn't even vote for ObamaCare's original passage, knows he can't run and win in this climate. If it's this bad for him, imagine how bad 2014 will be for the vast majority of Democrats who actually supported ObamaCare from its start," said Walden in a statement.
Rep. Steve Israel of New York, the chairman of the rival Democratic Congressional Campaign Committee, praised Matheson.
"For his entire career in public service, Jim Matheson has been putting his constituents first, and it's been an honor to serve with him. Jim's priorities have always been to focus on working together to solve our problems, responsibly put our fiscal house in order and make our country strong for the next generation," said Israel in a statement.
But Israel made no mention keeping the district in party hands.
Minutes after Matheson's announcement, the Rothenberg Political Report, one of the top non-partisan political handicappers, switched their rating of the race from "tossup" to "safe R."
Utah's third congressional district is reliably red in presidential elections, with Sen. John McCain and Mitt Romney easily carrying the district in the 2008 and 2012 contests.
Matheson becomes the first House Democrat to announce his retirement at the end of the term. Seven House Republicans have announced they will not run for re-election next year.
CNN Political Editor Paul Steinhauser contributed to this story.