A week from polling day in the by-election triggered by disgraced Chris Huhne's resignation, the prime minister will hold a Cameron Direct question-and-answer session with voters in the constituency.
The contest, pitting the Tory and Lib Dem coalition partners against each other, is seen as a key test for Cameron in the kind of seat his party needs to win if he is to get an outright majority in the next general election.
Both parties have thrown themselves into the contest, with a string of ministers and high profile figures filing down to Eastleigh to campaign, but there have been signs that the Lib Dems - who have a strong council presence in the area - have mobilised most effectively so far.
Mud-slinging between parties has hardly been tempered by their coalition at Westminster - a point underscored by Boris Johnson when he visited on Wednesday.
"I'm not in coalition with the Lib Dems - I truckle to no man," the Conservative mayor of London told reporters.
"I have no pact with these great quivering jellies. I am free to say what I think."
He said he hoped the Lib Dems enjoyed their power and their chauffeur-driven limousines because it allowed the Tories to get the policies through.
"The Lib Dems are wobbling jellies of indecision and vacillation, especially Clegg. His most spectacular contribution to British politics has been to make a U-turn on tuition fees and then make a song about it," Johnson said.
The by-election on 28 February was called after Huhne's resigned upon admitting he perverted the course of justice. Huhne - who faces prison when he is sentenced - held the seat for the Lib Dems at the 2010 general election with a relatively small majority of 3,864.