U.S. Rep. Van Hollen of Maryland announces Senate run

WASHINGTON (Reuters) - U.S. Representative Chris Van Hollen of Maryland announced on Wednesday that he would run in 2016 for the U.S. Senate seat held by fellow Democrat Barbara Mikulski, who is retiring. "I am very much looking forward to the upcoming campaign and a healthy exchange of ideas," Van Hollen said on his Facebook page. Mikulski, the longest-serving female senator in U.S. history with nearly 30 years in the upper chamber, said on Monday that she would leave office at the end of her fifth term in 2017. Political observers have floated several Maryland Democrats, including Van Hollen, as possible contenders to succeed the 78-year-old senator. Van Hollen, 56, has served in the U.S. House of Representatives since 2003 and is the top Democrat on the Republican-controlled House Budget Committee. He was seen as trying to move up the leadership ladder. Van Hollen is an ally of Representative Nancy Pelosi, the House's top Democrat, and had been mentioned as a possible speaker at some point if his party regained control of the House. The congressman would bring considerable fundraising power to a Senate run. Van Hollen is a former head of the Democratic Congressional Campaign Committee, which works to get more party members elected to Congress. Van Hollen, who represents Maryland's 8th District, said a formal announcement would follow. The Baltimore Sun first reported that he had told supporters by email that he planned to run. Other Democratic members of Maryland's House delegation, including Dutch Ruppersberger and John Delaney, have said they are considering runs. A spokesman for Delaney, Will McDonald, said in an email on Wednesday that the lawmaker is still strongly considering running despite Van Hollen's announcement. (Reporting by Emily Stephenson; Editing by Eric Walsh and Jonathan Oatis)