Baghdad, Iraq ? Radical cleric Muqtada al-Sadr has agreed to allow supporters to rejoin the Iraqi government after a three-week boycott, officials close to the militia leader said Thursday, as political rivals pushed to form a coalition without him.

Shiites from parliament’s largest bloc met Thursday in their holy city of Najaf to try to forge a new coalition across sectarian lines – one that won’t include al-Sadr’s supporters. They hoped, in part, to pressure al-Sadr to rejoin the political process and rein in his Mahdi Army militia, which is blamed for much of Iraq’s sectarian violence.

Fighting in Iraq claimed the lives of three more American servicemen, the U.S. military announced, bringing the U.S. toll closer to 3,000 on a day new Defense Secretary Robert Gates was in Baghdad to discuss strategy with military commanders.

In December, 71 American troops have been killed; at the current rate, the number of U.S. combat deaths this month could meet or exceed the monthly record for 2006.

Secretary of State Condoleezza Rice said in an interview that Iraq was “worth the investment” in American lives and dollars and said the U.S. still could win a conflict that has been more difficult than she expected.

“I don’t think it’s a matter of money,” Rice said. “Along the way there have been plenty of markers that show that this is a country that is worth the investment, because once it emerges as a country that is a stabilizing factor you will have a very different kind of Middle East.”

In the southern city of Najaf, delegates from seven Shiite parties appealed to Grand Ayatollah Ali al-Sistani, whose word is law to many Shiites, to support a planned governing coalition. The coalition would include Shiites, Kurds and one Sunni party – and bridge Iraq’s treacherous sectarian divide.

It seems likely that al-Sistani intervened to persuade al-Sadr to return to government and avoid a Shiite split. The Sadrist boycott has undercut Prime Minister Nouri al-Maliki’s government and prevented it from passing legislation.