Campaigning for two key parliamentary by-elections has entered its final week with all three main political parties talking up their prospects.
Mr Kennedy: People can give their view of the government
The polls are likely to be seen as a key test of public opinion on Tony Blair whose decision over Iraq is under also under the spotlight this week.
On Wednesday Lord Butler will publish his report on the use of intelligence in the run up to Britain going to war.
That follows Monday's spending review which Gordon Brown will outline to MPs.
Liberal Democrat leader Charles Kennedy said Thursday's polls were a chance for voters in Leicester South and Birmingham Hodge Hill to "express their absolute state of sick and tiredness with the government".
"That includes everything from Iraq, the trust factor through to the quality of local public services," he told the BBC's Breakfast with Frost programme.
His party had given Labour a "jolly good run for their money".
"But it could be nip and tuck, it could be close," he said.
'On the up'
Mr Kennedy added a result that showed a "significant and a substantial increase" in support for his party would play in their favour in the run-up to a general election widely predicted for next year.
The Conservatives' campaign manager in the Hodge Hill by-election, Andrew Mackay MP, said his party was "on the up" in Birmingham.
The long-time Labour MP died in May
He told BBC One's Politics Show: "We've been second in this constituency at every general election since the war.
"We won it in the by-election in similar circumstances.
"The Conservatives have just taken control of the city council for the first time in 20 years.
"Tories in Brum are on the up at the moment and we're working very hard to make sure that continues."
Labour is defending what are normally two of its safest seats on Thursday. The Leicester South by-election was triggered by the death of long-serving MP Jim Marshall from a heart attack in May.
In Birmingham Hodge Hill, Labour's Terry Davis - who held the seat at the 2001 general election with a majority of 11,618 - is stepping down to become general secretary of the Council of Europe.
Monday's spending review is a key political event in which Chancellor Gordon Brown will set out government spending plans for the next three years.
Mr Davis quit after landing himself a new job
The Butler Inquiry meanwhile reports on the eve of the two by-elections.
The respected former civil servant has been leading a key probe into the way intelligence about Iraq's alleged weapons capability was used.
On Sunday key cabinet ministers went on a media offensive defending Mr Blair and dismissing suggestions he had considered resigning.
Health Secretary John Reid said: "He will lead us into the next general election and, God and the electorate willing, will be prime minister in this country for many years to come."