The number of Tory MPs who want to withdraw from the EU is growing, claims Euro-sceptic MP Philip Davies.
There has been little debate over the EU at the Tory conference
He says David Cameron is also happy for MPs to advocate that policy without fear of any sanctions inside the party.
Meanwhile Edward Leigh warned Tories could become recruiting agents for UKIP and the BNP if they do not speak up on tax, Europe and immigration.
He urged the leadership to pay attention to its traditional right-wing voters, or risk losing them.
The two Tory MPs were speaking during separate fringe meetings at the party's annual conference in Bournemouth.
Mr Davies, one of six Tory MP members of the Better Off Out group - which advocates the "positive benefits" for Britain to be outside the EU - said: "There are now 10 MPs who will openly say that Britain should leave the European Union.
"There are many more of us who think it and one of my jobs is to persuade them to have the courage of their convictions and actually publicly say it as well.
"And I just want to at this point actually praise David Cameron because to be fair to [him] he has been the first Conservative leader who has actually said quite openly that backbench MPs are free to advocate Britain's withdrawal from the European Union without any repercussions whatsoever and that has enabled this debate to take place."
And Mr Leigh, chairman of the influential Commons Public Accounts Committee, argued that the issue of Europe was "not something you can turn down the volume on".
"Europe is a real issue that we must go on talking about."
He said it was vital if the party was to win the next election that it remained loyal to its core supporters.
"You can't just assume that your traditional voters will remain on your side," he said.
He also told the right-wing Cornerstone group fringe that the Conservatives were "nothing" if they did not want to return more of taxpayers' money to them.
His message came after shadow chancellor George Osborne said he was ready to take on those elements of the party who are demanding tax cuts.
He said he was not prepared to be "pulled or pushed around".
Mr Leigh said Chancellor Gordon Brown, widely tipped to be the next prime minister, would capitalise if the leadership did not make the case for a smaller state.
"Unless you make that case now we will lose the next election," he said.
"Gordon Brown will say, 'look at those Tories - they want to make tax cuts, the cake is only so big'.
"And the people will believe him."
Mr Leigh added that many people had been disappointed that there was no mention of immigration in Mr Cameron's Built To Last mission statement for the party.
He said the issue could not be seen as racist, because most of the influx was from Europe. However, the number of people coming in was alarming.
"The party must speak up on immigration," he said.
"If we don't speak out on these issues there's a real danger that we can become a recruiting agent for UKIP and BNP."
He added: "Of course you've got to be on the centre ground in politics, but you've got to drag the centre ground towards you."
Mr Leigh said his concerns about the leadership's direction were shared by a large section of the party.
"I think there's a massive appetite among the parliamentary party and the grass roots talk about these issues," he said.
David Cameron said earlier on Tuesday that he wanted to concentrate on issues such as flexible work rights for parents rather than "banging on about Europe".