BAGHDAD — Radical Shiite politicians pressed Thursday for legislation demanding a timetable for the withdrawal of U.S.-led troops and a freeze on the number of foreign forces already in the country — even as the U.S. Congress debates the fate of the troubled mission.

The proposed Iraqi legislation, drafted by the parliamentary bloc loyal to anti-American Shiite cleric Muqtada al-Sadr, was signed by 144 members of the 275-member house, according to parliamentary officials.

The Sadrist bloc, which holds 30 parliamentary seats and sees the U.S.-led forces as an occupying army, has pushed similar bills before, but this would be the first time it persuaded a majority of lawmakers to sign on.

The measure has not yet been introduced in parliament and was unlikely to be passed in its present form. But the signatures reflected growing disenchantment among the lawmakers over U.S. involvement in Iraq and the government's failure to curb the violence in the country.

It also appeared part of a campaign by al-Sadr's followers to carve out a strong opposition position after they quit Prime Minister Nouri al-Maliki's Cabinet last month over the government's refusal to demand a timetable for the U.S. to leave.

The White House questioned whether Sadrists had the votes in parliament.

"The president of Iraq, the vice presidents, and the prime minister all support keeping U.S. troops in Iraq," National Security Council spokesman Gordon Johndroe said in Washington. "The Sadrists often makes these claims, yet rarely produce a bill, let alone a majority."

The discussion over a troop withdrawal came as a series of evening explosions rocked Baghdad, killing at least two people. A total of 35 people were killed or found dead nationwide Thursday.

The military announced that three more U.S. troops had been killed. Two soldiers were killed by gunfire Thursday — one in Baghdad and the other in Diwaniyah — and a Marine died Wednesday in combat in Sunni-dominated Anbar province.

Despite al-Sadr's bill, Shiite parties still represented in the Cabinet are not keen to see U.S. troops leave until Iraqi forces are ready to take over security. Al-Maliki relies heavily on U.S. support to hold his factious administration together.

Ali al-Adeeb, a senior Shiite lawmaker and confidante of al-Maliki, was skeptical about the wisdom of asking foreign forces to leave.

"Their withdrawal will not benefit anyone if our forces are not ready," al-Adeeb said.