Liberal Democrat leader Nick Clegg sought to kill talk of a post-election deal with the Tories amid signs it would provoke an angry backlash from his party.
As expectations of a hung parliament grew, the Lib Dems' final conference before the general election expected on May 6 was dominated by speculation about a coalition government.
Delegates in Birmingham have made clear, however, their strong animosity towards the Conservative Party.
Lib Dem MPs warned privately that a majority of the parliamentary party would not support Mr Clegg if he entered a formal coalition with the Tories.
In his keynote speech at the close of the three-day gathering, Mr Clegg rowed back from any impression that he was courting either the Tories or Labour. "I am not the kingmaker," he insisted. "The 45 million voters of Britain are the kingmakers. They give politicians their marching orders, not the other way round."
Insisting that the Lib Dems were not a "wasted" vote, he suggested that the party was in fact a small step from emerging as the dominant force in the House of Commons.
"Almost one in four voters chose the Liberal Democrats at the last election. If that increased to one in three, we could lead the next government," he insisted. "This election is a time for voters to choose, not a time for politicians to play footsie with each other. The party which gets the strongest mandate from the voters will have the moral authority to be the first to seek to govern."
He pointed to the fact that 32% of people did not vote for Labour or the Tories at the last general election as evidence that the two-party system was giving way.
However, two new polls showed that Mr Clegg was well short of winning a third of the popular vote. According to ICM they were on 21%, and according to YouGov just 17%.
The polls also indicated that the Tories' lead over Labour - at, respectively, four points and seven points - was not enough to guarantee Mr Cameron a clear Commons majority.
UK 
