Buried in the small print of the new Telegraph poll on marginals  is this revealing finding:
The poll found that the Tories would pick up 74 of the 100 seats from Labour. However, they would not pick up any of the seats held by Liberal Democrats.
To secure a majority in the Commons, the Conservatives need to win no fewer than 117 seats. So if, as this poll suggests, they fail to win any of the 20 key Lib Dem-Tory marginals, they will struggle to prevent a hung parliament.
Thus, the Telegraph's claim that the Conservatives are "are on course for a convincing election victory" is not supported by the facts.
It's not surprising that the Tories are struggling in these seats. First, many Lib Dems MPs have large local followings and a deserved reputation as dogged campaigners. Second, in a significant number of these seats the Tories are not in second place, but third, putting them out of the party's reach.
That Nick Clegg's party could still prevent a Conservative majority explains why the Tories are spinning the line that a vote for the Lib Dems is a "vote for Labour".
Both Gordon Brown and David Cameron would love to go in hard against Clegg in tonight's live TV debate. But they'll both need his support in the event of a hung parliament, so they're more likely to concentrate their fire on each other.