BEIRUT, - After two humdrum rounds of legislative elections, Lebanon is poised for a heated contest Sunday that could determine whether an anti-Syrian coalition will muster a parliamentary majority and maintain momentum to thrust the country into a new era.

In the most critical round of a four-phase election, Christian and Muslim voters in the central Mount Lebanon region and the eastern Bekaa Valley will decide on nearly half of the 128 seats in parliament.

At stake domestically is the new legislature's ability to dislodge remnants of Syrian control, after a 29-year military presence, from key institutions including the presidency. Syrian troops withdrew from Lebanon this spring, but the country continues to wield considerable influence.

"Syria is out of our geography, but not out of our politics or the region's geopolitics," Rafik Khoury, a columnist with the Al Anwar daily newspaper, said in an interview. "The difference is that a year ago, we were on death row. Now our sentence has been reduced to a one- or two-year prison term."

BEIRUT (Reuters) - Voters head to the polls in central and eastern Lebanon today (Sunday) , where anti-Syrian factions are squaring off against each other in the most crucial round of Lebanon's parliamentary election.

With 58 seats up for grabs in the Mount Lebanon and eastern Bekaa Valley districts, the shape of the next 128-seat assembly should become clear in the penultimate stage of Lebanon's first general election since Syria pulled its troops out.

Forty-two legislators have already been elected in the first two rounds of voting in Beirut and south.

Those rounds brought no surprises, with the son of slain former Prime Minister Rafik al-Hariri winning a landslide in the mainly Sunni capital and a joint Hizbollah and Amal slate sweeping polls in the southern Shi'ite heartland.

President George W. Bush issued a new warning to Syria to withdraw its forces from Lebanon, with the White House saying the Damascus government was having an intimidatory impact as Lebanon stages elections.

Bush said he was "disturbed" by reports that Syrian intelligence remain in Lebanon, in breach of a UN resolution ordering all Syrian forces out of the country.

"Our message to Syria -- and it's not just the message of the United States; the United Nations has said the same thing -- is that in order for Lebanon to be free," Syria needs to "not only remove their military, but to remove intelligence officers as well," Bush said at the White House.

BEIRUT (AFP) - Syrian intelligence agents remain in Lebanon despite assurances they have left, and more political murders can be expected, a key opposition figure said in a claim echoed by Washington.

"I believe the entire opposition is being targeted," said Druze leader Walid Jumblatt in a television interview late Thursday night, repeating an accusation he has often made since the murder in February of former premier Rafiq Hariri.

"The assassinations will continue with or without the knowledge of Syrian President Bashar al-Assad," he charged.

Jumblatt was speaking only a week after the latest political killing -- the death of prominent anti-Syrian journalist Samir Kassir.

Lebanon's pro-Syrian regime and its political masters in Damascus have denied widespread allegations that they were behind the two killings, as well as a series of bombings since Hariri's death that have killed three others.

But Washington voiced concern over what it said was a continued Syrian intelligence presence in Lebanon, charging that it was creating a climate of fear in the midst of parliamentary elections.

"We are deeply concerned about Syria's interference and intimidation inside Lebanon," White House spokesman Scott McClellan told reporters.

"Syria needs to comply fully with United Nations (Security) Council Resolution 1559 -- that means getting all their intelligence operatives out of Lebanon," McClellan said, referring to a US- and French-sponored text adopted last September.