Weekend opinion polls have suggested that Labour continues to hold a significant lead over the Conservatives.

With the political parties now in election mode ahead of a poll widely expected to be held on May 5, Tony Blair's party continues to retain the support of more voters.

And there was additional mixed news for Tory chief Michael Howard.

A CommunicateResearch poll for the Independent on Sunday suggested that the tough Conservative stance on immigration and asylum could win the party more votes.

An ICM poll in the Sunday Telegraph also found widespread dissatisfaction with the government's handling of immigration issues.

But a MORI survey for the Observer found that just 22 per cent of those questioned were satisfied with Howard's performance as leader. In contrast, some 48 per cent said they were dissatisfied.

All three polls showed a significant lead for Labour, with the Liberal Democrats also performing strongly.

The Independent on Sunday's polling put Labour on 40 per cent, the Conservatives on 32 per cent and the Lib Dems on 20 per cent.

According to the Sunday Telegraph, support for Labour stands as 37 per cent, the Tories are on 32 per cent and the Lib Dems on 21 per cent.

The Observer's figures showed Labour on 38 per cent, the Conservatives on 32 per cent and the Liberal Democrats on 22 per cent.

Should these levels of support be duplicated on polling day, the prime minister could be returned to Number 10 with another three-figure majority.

Howard's blues

Meanwhile, the ICM poll found that 18 per cent of people were more likely to vote Conservative following the party's pledge to get tough on immigration.

That compared with 68 per cent who said the policies made no difference to their intentions and 12 per cent who said they were now less likely to back the party.

In contrast, the Independent on Sunday's poll found that 71 per cent felt the government does not have immigration and asylum under control

And 41 per cent said that the issue might change the way they vote in the next general election.

The polling also delivers a damning verdict on Howard's leadership of the Conservatives.

MORI found that only 22 per cent were satisfied with the job he was doing as leader, compared to 48 per cent who were dissatisfied.

Orange future?

One complicating factor for those seeking to predict the next election result, however, is the possible performance of the Liberal Democrats.

The CommunicateResearch polling found that while a fifth of voters currently back Charles Kennedy's party, an extra 17 per cent would give their support if the Lib Dems has a "realistic" chance of winning the constituency.

Some 29 per cent of Labour supporters and 19 per cent of Conservatives say they could make the switch to the Lib Dems.

The Independent on Sunday suggested such a result could lead to electoral "meltdown", with the Lib Dems forming the next government and the Conservatives left with just 56 seats.

Liberal Democrat campaign chairman Lord Razzall said the poll "confirms that three party politics are here to stay".

"Charles Kennedy has made clear that there is no artificial limit to our ambitions," he said.

"For the Liberal Democrats there is everything to play for in the next general election."

EU poll battle

ICM in the Sunday Telegraph also found that the battle over the EU constitution could be closer than expected.

With the vote expected in spring of 2006, the poll found that some 39 per cent would currently vote yes and 41 per cent would say no.

The finding was not in line with previous polls, which have found significant majorities against the constitution.

However, it was the first poll which put the actual referendum question to members of the public.

Ministers revealed last week that the question will be: "Should the United Kingdom approve the treaty establishing a constitution for the European Union?"