By Iain Watson
Political correspondent, BBC News
Conservative MP Anne Main will later attempt to save her political career as she faces her critics at a local party meeting.
Anne Main is fighting for her political life
But although she is currently being investigated by Parliament's standards watchdog, the attempt to deselect her may have as much to do with her slender majority - and fears of losing the St Albans seat to the Liberal Democrats at the next general election - as anything she did or did not claim on expenses.
And her supporters are attempting to fight fire with fire by mounting a bid to strip constituency chairman Seema Kennedy and her deputy, Matthew Peck, of Conservative Party membership for having the audacity to put down a motion of no confidence in a sitting MP.
So by about 2200 BST we will know whether Mrs Main's career - or that of two of her local party's top office holders - have been cut short by the continuing fallout from the expenses scandal.
It could be a stormy meeting.
Anne Main took this Hertfordshire seat from Labour in 2005 - but she has a majority of just 1,361 and now the third placed Liberal Democrats, who have been doing well in local elections, have high hopes of depriving her of victory at the next general election.
She hit the headlines, along with many other MPs, in May when the Daily Telegraph said she was claiming expenses for a constituency flat in which her daughter sometimes lived rent-free, and that her principal home was just 25 miles away around the M25 in Buckinghamshire - a distance which her critics say makes her second, taxpayer-funded, constituency home unnecessary.
Mrs Main responded with a familiar refrain - that the Commons' authorities had approved the arrangements.
She claims she was cleared by the Conservatives' internal scrutiny panel and she was not forced to pay money back, unlike several other Tory MPs whose claims were within the rules but had been judged harshly in the court of public opinion.
But still faces a further investigation by the Parliamentary standards commissioner following a formal complaint about her expenses from a constituent.
And her opponents in St Albans - who fear more bad headlines lie in wait - are attempting to get rid of her before the watchdog delivers his verdict.
When details of Mrs Main's expenses were first published few in her local party got hot under the collar.
But they became rather less relaxed after June's county council election results.
The Conservatives did well across most of England - and indeed performed well in many parts of Hertfordshire - but within the boundaries of the St Albans constituency, two seats were lost to the Lib Dems and no seats were gained.
In a letter to all 300 members of Anne Main's Conservative association in St Albans - a copy of which has been obtained by the BBC - the constituency's vice-chairman Matthew Peck says he was given private polling from Conservative Central Office which suggested the seat was now vulnerable to the Lib Dems at the next general election.
In the letter, he states: "I am writing to explain the reasoning behind my actions as Deputy Chairman Political, and as a response to attempts to remove me from my post. The initial actions to deselect Anne Main were as a direct result of information about poll data obtained by Central Office informing us that our seat is likely to be lost to the Liberal Democrats, with a significant contributing factor being the public's perception of Anne Main's expenses claims....
"We have already experienced the publics wrath during the County Council elections, and I believe we can expect more of the same when it comes to a general election....Until this matter is resolved Anne's position and authority is significantly weakened and is in effect a "lame duck" MP. The Liberal Democrats will be very aware of this issue as we approach the election, they will play it entirely to their advantage and be able to pull over a disproportionately large share of the collapsing Labour vote."
Mr Peck and party chair Seema Kennedy had already asked Mrs Main to go quietly following the local elections, in which both of them had failed in their respective bids to gain a seat on the county council.
She ignored their pleas - but although she has the backing of the majority of the 40-strong executive committee of local party activists, all 300 hundred constituency party members will have their say later.
Chris Baker, who failed in his bid to become a Tory councillor at the local elections, told BBC News he would be voting to deselect Mrs Main.
He stressed it was for political rather than personal reasons, saying he had met people on the campaign trail who had voted Conservative at the 2005 general election but were no longer willing to do so because of the expenses issue.
Mrs Main will, in effect, be reapplying for her job when she addresses Thursday night's meeting - but her supporters say she will not get into a slanging match with her opponents and will simply speak about her positive record as a member of Parliament.
If her opponents fail in their bid to remove her, they themselves could be ousted from their positions within the local party - and may even be suspended from party membership.
Once the meeting to discuss Anne Main's deselection concludes, there will be a further meeting to discuss their future.
Mrs Main's opponents have rather colourfully complained of "Robert Mugabe tactics" to silence the local dissidents, though so far any assaults have been purely verbal.
Mrs Main herself does not intend to speak openly of the Conservatives' internal struggles until after her future has been decided.
But it is clear that the whole issue of MPs' expenses did not disappear when the Daily Telegraph finally took the story off its front page.