We’re due a set of opinion polls this week from Liberal Democrat-Conservative marginal seats.

The survey has been commissioned by Lord Ashcroft, who has dropped no hints about the results other than they will be made public within the next few days*.

I’m not sure whether the polls will just cover Lib Dem seats where the Tories are in a close second place, or may also include constituencies where the reverse is true and the Lib Dems are close behind the Tories.

Whatever the exact nature of the survey, its findings will be intriguing for the snapshot they will provide of the state of play in some of the election’s key battlegrounds.

Here are the Lib Dems’ seats most vulnerable to the Conservatives:

One of the biggest of the big unknowns about next year’s election is whether the Lib Dems’ ongoing slump in the polls will be at all matched by a slump in the party’s number of MPs. All of the 10 seats listed above would fall on a swing to the Tories of 3%. But were such a swing to occur nationwide, roughly 40 Labour seats would also fall to the Tories, and we’d get a Conservative government with a majority of around 30.

I still think it more likely that Lib Dem seats will fall to Labour than the Tories. I say this based on how the respective parties have performed in local elections over the past few years, and also because the nature of the Lib Dems’ relationship with the Tories at Westminster could well mean the party’s natural supporters behave less consistently in marginal seats. People who voted Lib Dem in 2010 may be more likely to stick with the party in seats where the Tories are the main challenger than in those where Labour is in second place.

For comparison, here are the Tories’ seats most vulnerable to the Liberal Democrats:

A slightly smaller swing (around 2.5%) would see these change hands. It’s tempting to say there is almost no chance of this happening. But don’t rule anything out. We may see the Lib Dems pick up a couple of these seats at the same time as losing a couple of dozen more, meaning the party ends up with an overall net loss of 20. In particular, George Eustice in Camborne & Redruth and Nicola Blackwood in Oxford West & Abingdon certainly shouldn’t take re-election for granted.

One thing’s for sure about this week’s forthcoming polls: they will feed the Clegg-in-crisis narrative in some way, and further compound the impression of a party lurching rather than roaring through the final 12 months of government.

*Update: Lord Ashcroft has said that the poll results will be released at 11am on Thursday.