After London Attack, PM May Continues to Slide in U.K. Polls Ahead of Election

May's Conservatives held 330 seats in the Parliament when she called the snap election; now they are projected to win 305 seats

Britain's Prime Minister Theresa May speaks outside 10 Downing Street after an attack that left 7 people dead and dozens injured in London, June 4, 2017.

Prime Minister Theresa May is on track to win 305 seats in Britain's parliament in an election on Thursday, 21 seats short of a 326-seat majority, according to a projection by polling company YouGov on Monday.

May's Conservatives had 330 seats when the snap election was called in April. 

The lead of May's Conservative Party over the opposition Labour Party has narrowed slightly to 11 percentage points before election, according to an ICM poll published in the Guardian newspaper on Monday. 

May's lead slipped from a lead of 12 percentage points in a previous ICM/Guardian poll published a week ago. 

In the new poll, support for the Conservatives stood at 45 percent, unchanged from last week, and Labour was on 34 percent, up one point. 

The latest poll was conducted between June 2 and June 4, so some of the responses would have been gathered after an attack by Islamist militants in London on Saturday that killed seven people and injured 48. 

On Saturday, YouGov said its model suggested the Conservatives were on course to win 308 seats. 

The opposition Labour Party is likely to win 268 seats, YouGov's model showed on Monday, up from 261 on Saturday. 

Another model, produced by Lord Ashcroft Polls, last week predicted the Conservatives were on course for a majority.