Tony Blair's victory in Britain's national election Thursday may turn bittersweet if the Labour Party's diminished majority in Parliament sets the stage for anti-war critics within the party to oust him as prime minister.

Labour beat the main opposition Conservatives with a sharply reduced majority — apparently reflecting an electorate intent on punishing Blair for dragging the nation into the Iraq war but still willing to keep his party in power.

With vote counting still under way early Friday, official partial results showed Labour won enough to form a government. Exit polls predicted Labour would wind up with less than half its current 161-seat margin.

Deprived of his comfortable parliament majority — and facing a faction in his party willing to vote against him on key policy issues — Blair is likely to come under strong pressure in the middle of his four-year term to give way to his more popular Treasury chief, Gordon Brown (search).

Brown is widely considered the architect of Britain's current economic boom — the longest period of expansion in the nation's postwar history.

He is reported to covet the prime minister's post and would be the heir apparent because the main factor in Labour's victory is probably its record on increasing prosperity, creating business opportunities and keeping workers in their jobs.

Blair may now be seen as damaged goods for Labour — possibly prompting it to bring in Brown sooner rather than later to allow him time to shore up his leadership looking toward the next election.

The Conservatives, led by Michael Howard (search), tried to win voters by accusing Blair of lying about the case for invading Iraq and promising to be tough on crime and immigration — running a campaign of arguably unprecedented aggressiveness.

But the Tories were hampered by several factors: They themselves backed the Iraq war, their pro-business economic policies have largely been adopted by Blair's party and their relatively conservative social positions seem to many voters to be a relic of bygone age.

Moreover, Howard is the latest in a string of bland Conservative leaders who have been unable to match Blair's more media-savvy campaigning style.

"If this prediction were true, it is clear that the public want to cut Tony Blair down to size and make him more accountable," said Tory co-chairman Liam Fox.

Blair, who became prime minister in 1997, also may have benefited from an electoral system stacked in its favor.

In Britain, each of the nation's 646 electoral districts sends one lawmaker to the House of Commons (search). Whoever wins the most votes in each district gets the seat, and the party that gains the most Commons seats forms the government.

That put the Tories at a disadvantage because a large portion of Conservative supporters are in rural districts where the Tories always win by a heavy margin, thus "wasting" votes. Labour's support is efficiently distributed across far more constituencies.

As they voted, some voters say they were casting their ballot for Labour in the expectation they will soon have a Prime Minister Brown.

"Brown is cut from the same mold as Blair and is going to continue the same policies, but he doesn't have the baggage that Tony Blair has," said Stewart Willn, 27.