David Cameron has entered the fray for the first time in the hotly contested Eastleigh by-election battle.
The Tories are hoping to take the seat from their Liberal Democrat coalition partners in a contest triggered by the resignation of disgraced ex-Cabinet minister Chris Huhne, following his conviction for evading speeding points.
In a question and answer session at B&Q's UK headquarters in Eastleigh, Mr Cameron described the Tory candidate Maria Hutchings as a "decent person who tells it like it is".
Ms Hutchings has however already ruffled feathers in the Conservative high command by speaking out against Mr Cameron's plans for gay marriage and suggesting she would vote for Britain to leave the EU.
Nick Clegg has already made his first foray into the Hampshire constituency, with further campaign visits expected - underlining how high the stakes are for both leaders.
A win for the Conservatives would help to convince restive Tory backbenchers that Mr Cameron still has a chance of leading them to outright victory at the next general election. Equally Mr Clegg needs the Lib Dems to hold the seat if he is to reassure supporters that they are not facing a catastrophic collapse the next time the country goes to the polls.
The Prime Minister insisted the result of the by-election would not change the Government, but said it was important for the people of Eastleigh to elect the best candidate to represent them in the Commons.
Mr Cameron spoke of how he got to know Ms Hutchings in 2005 when he became shadow education secretary. He said they met to discuss special education needs as she has two disabled children.
"I saw in the meetings I had with Maria then someone who was passionate, someone who really cared, someone who thought not just about her own family but about other families and how they were going to cope," he told the audience. "The most important thing is who knows this area, is going to stand up for it and is a thorough, decent person who tells it like it is? That is what you'll get with Maria."
Ms Hutchings said she had worked on behalf of people in Eastleigh for several years and would "put everything" into the role if she wins the election. She added: "I will be an MP that you can trust, that will truly understand your constituency and put your issues first. A good voice for you in Parliament."