For someone who has never served in Congress, Mitt Romney is rounding up the Capitol Hill endorsements.

Senators Olympia Snowe (R-Maine) and Richard Burr (R-N.C.) at the Capitol. Burr endorsed former Massachusetts governor Mitt Romney (R) on Thursday. (REUTERS/Benjamin Myers)

Burr, a 17-year Capitol Hill veteran who served five terms in the House before winning election to the Senate in 2004, backed Sen. John McCain (R-Ariz.) four years ago. His endorsement of Romney this time around follows another key Tar Heel win for Romney – former senator Elizabeth Dole, who endorsed him earlier this month. Dole’s husband, former Kansas senator Bob Dole, has also announced his support for Romney.

“The lack of leadership from the current Administration has had a devastating effect on our nation, our economy, and on American families across the country,” Burr said in a statement Thursday. “Governor Romney is a strong leader with a proven track record of addressing the most pressing issues of our time – growing the economy and creating jobs for American workers. I am proud to give him my support, and I am confident he will be our next president.”

North Carolina’s primary is still more than four months away: It comes on May 8, by which time all but 13 states will have held their nominating contests.

The endorsement means that Romney has won the backing of nearly a quarter of all Senate Republicans. He also has the support of 49 House Republicans, or about one-fifth of the House GOP conference.