BAGHDAD, Iraq (CNN) -- Authorities said at least 86 bodies were found in the Iraqi capital during a 30-hour period ending midday Tuesday, sparking fears that sectarian reprisal killings are continuing at a grisly pace.

With Iraq's newly elected parliament set to meet Thursday, officials announced a vehicle curfew. Authorities will stop any car or truck in Baghdad between 8 p.m. (noon ET) Wednesday and 4 p.m. (8 a.m.) Thursday.

Police found 29 bodies on the eastern side of the capital in a Shiite neighborhood.

Fifteen bodies also were found Tuesday morning in a truck in a Sunni neighborhood in western Baghdad, police said. The victims were all males between the ages of 25 and 40, authorities said.

Another two bodies were discovered in southern Baghdad.

Police counted the recovery of 40 bodies during the 24 hours that ended at 6 a.m. Tuesday (10 p.m. ET).

"The indications are, police won't say this, but the indications are that these are sectarian killings," CNN senior international correspondent Nic Robertson said. "... You talk to some people here in Baghdad and they talk in their neighborhoods, mixed neighborhoods, of tit-for-tat killings. Sunni one day, Shia the next day...

"That's the perception in the city at the moment."

Sectarian violence has gripped the capital, home to 6 million Iraqis, and flared in other cities since the February 22 bombing of a revered Shiite mosque in Samarra.

The latest wave of killings follows Sunday's string of car bombs in Sadr City, Baghdad's huge Shiite slum, that killed at least 46 people and wounded more than 200 others.

Bush fights lowest rating

President Bush launched a new effort to shore up support for the increasingly unpopular war in Iraq on Monday.

The speech at George Washington University was the first of a series of planned appearances the White House is hoping will turn around a longstanding slide in support for the war, a week away from its third anniversary.

A CNN/USA Today/Gallup poll released Monday found only 36 percent of Americans approved of Bush's performance in office -- a new low for his presidency in that poll -- and 57 percent said they considered the March 2003 invasion that toppled Iraqi leader Saddam Hussein a mistake.

Only 32 percent of those polled from Friday through Sunday said they thought Bush had a clear plan for handling the situation in Iraq, while 67 percent said he did not.

But Monday, Bush said U.S. forces were "making progress" in the war, building up Iraqi troops and finding ways to counteract the roadside bombs behind a large proportion of U.S. casualties.

He also praised Iraqis for averting civil war despite the sectarian violence after the Samarra mosque bombing. "The situation in Iraq is still tense, and we're still seeing acts of sectarian violence and reprisal," Bush said.

"Yet out of this crisis, we've also seen signs of a hopeful future."