When Nancy Pelosi becomes Speaker of the House, Democrats will have to fill the position of majority leader. The complex contest pits Pennsylvania Democrat John Murtha, who has become one of the chamber’s most outspoken advocates for getting U.S. troops out of Iraq, against Maryland Democrat Steny Hoyer, the current Democratic whip in the House and a much more cautious critic of the Bush administration’s handling of the war.

Most House Democrats tend toward Murtha’s position on the war. But, by and large, they tend to be more socially liberal than Murtha on issues such as abortion rights and gun control, a circumstance that has led some war foes — including “Out of Iraq Caucus” founder Maxine Waters, D-California — to back Hoyer.

How to sort the choice out? Pelosi wants to help. In a rare move for someone in her position — earlier this year, House Speaker J. Dennis Hastert, R-Illois, sat out the contest to replace disgraced House Majority Leader Tom DeLay, R-Texas, after DeLay resigned — the top Democrat has made an endorsement.

Despite previously expressing frustration with Murtha’s decision to challenge Hoyer, Pelosi on Sunday weighed in for her longtime ally from Pennsylvania. Sending a signal that she thinks the Iraq debate is going to be central to the new Congress, Pelosi wrote Murtha an endorsement message that read: “I salute your courageous leadership that changed the national debate and helped make Iraq the central issue of this historic election. It was surely a dark day for the Bush Administration when you spoke truth to power. Your strong voice for national security, the war on terror and Iraq provides genuine leadership for our party, and I count on you to lead on these vital issues.”

The letter was circulated late Sunday by Murtha’s office. It had to sting Hoyer, who jousted with Pelosi in a previous leadership contest and who has generally been seen as the leader in this race.

The vote by the full House Democratic Caucus is expected to take place Thursday.