Labour and the Conservatives were this week reviewing their election strategies after the surge of support for Liberal Democrat leader Nick Clegg.
As PRWeek went to press, polls suggested the rise in Lib Dem support was damaging both parties.
However, Labour and Tory strategists have been reluctant to attack Clegg amid concern of being accused of 'the old politics'.
Writing in PRWeek, former Labour special adviser Paul Richards said his party could 'only stick to the game plan'.
Labour strategists believe the party should continue to highlight the threat to the recovery posed by the Tories. But Labour's new fear is that the election could turn into a contest between two parties of change - with Labour trailing as the party of the establishment.
Meanwhile, the Tories are urged by former comms chief Tim Collins to embrace more radical policy positions to show that they can deliver real change.
Collins' comments follow his Bell Pottinger colleague Peter Bingle sending out a memo describing the Tory campaign as 'the most inept in living memory' and urging the Tories to speak more about immigration. However, Tory high command is nervous about being seen to drift too far to the right.
Cameron underlined the jitters felt in the Tory leadership this week by changing a party election broadcast at the last minute.
Labour claimed seven statements made by Cameron in this week's TV broadcast had been plagiarised from Clegg.
For the Lib Dems, former adviser Ian Wright says the party may be hoping that 'many people have firmly made their minds up already'.
A Lib Dem comms insider told PRWeek there was 'a slight sense of shell shock' at party HQ, adding that Clegg would 'take the opportunity to put forward a positive Lib Dem platform'.
1.66#/ Odds on Nick Clegg winning second TV debate
9/1 Odds on Gordon Brown winning second TV debate
10/1 Odds on Lib Dems winning most seats in general election
Ladbrokes' odds at 5pm, 20 April
PRWEEK ELECTION PANEL
Leading comms experts, with different allegiances, give their verdict so far
- Paul Richards - Labour
If Nick Clegg is the answer, I'm not sure we are asking the right questions. His ability to speak to camera and remember audience members' names is the stuff of presentation skills seminars. It does not make him the 'new Obama'.
Labour's response to the media Cleggathon has been steady. All those mugs and posters at Victoria Street with 'Keep Calm and Carry On' have been taken to heart. Labour can only stick to the game plan: keep banging on about the economic recovery and the risk posed by a Tory Government. It is impossible for Labour to calibrate a response to Clegg. A small Lib Dem revival helps Labour become the largest party; a bigger Clegg bounce delivers a Tory victory.
Either way, the only certainty on 6 May is that Clegg will not be PM, no matter how well he performs on TV. The polls, despite Labour coming third, suggest Brown will be back in Downing Street. No wonder he looks relaxed and happy. For the first time in years, he is not staring down the barrel of a Tory victory.
Richards formerly advised cabinet ministers Patricia Hewitt and Hazel Blears, and is the author of How to Win an Election. He writes a weekly column for Progress
- Tim Collins - Conservatives
This election is now seriously off-piste.
Everyone expected a small short-term bounce for the Lib Dems by giving them an equal platform in the debates - not a sustained double-digit surge.
The threat to Conservative strategy is obvious. But there is an opportunity too. Appetite for change is clearly immense. Incumbency offers no benefits to sitting Labour MPs. Readiness to change the Government is at an all-time high. Ministerial claims that only they can be trusted on the economy have boomeranged: they are the first Government to run third in repeated polls in a campaign.
On issue after issue, the two left-wing parties offer continuity with the post-1997 settlement. Only the Tories offer a radical break with the past 13 years, from public service reform to immigration limits, from tax to policing, from Europe to planning. David Cameron started well on this with his personal PPB - now all in his party need to follow through. Caution will no longer produce a Conservative win. Boldness still can.
Bell Pottinger Public Affairs MD Collins is a former Conservative Party comms director and has served in the shadow cabinet
- Ian Wright - Liberal Democrats
I closed last week with the suggestion that the TV debates had the potential to be the real game-changer for the whole campaign. So it proved. Nick Clegg deployed an 'outsider' strategy, used the language of ordinary conversation rather than the political speak of his opponents, and most effectively bundled Brown and Cameron together.
The result was probably the most remarkable bounce in British political history. The landscape has been transformed and the next few days are totally unpredictable. The Tory response is clear. Use the popular press to undermine Lib Dem credibility by attacking them on tax, immigration and Europe.
While Cameron seeks to assert that he is the only realistic agent of change, Labour seems to hope that Clegg's surge will abate. For the Lib Dems, the hope may be that many people have firmly made up their minds already. In fact, they did in those crucial first three minutes when Clegg seized the chance to introduce himself direct to ten million voters.
Wright has advised Liberal Democrat leaders Paddy Ashdown, Menzies Campbell and Nick Clegg