MICHEL MARTIN, HOST:

And in the wake of all this, there are elections this week in the United Kingdom. On Thursday, voters will decide whether to keep Prime Minister Theresa May and her conservative party, the Tories in power. It's what's called a snap election, something like a special election in the U.S. The general election was due to be held by May of 2020, but Prime Minister May called for earlier elections saying she needed a strong mandate to manage the U.K.'s exit from the European Union, the so-called Brexit vote.

For most of the campaign, a victory has been seen as a fairly sure thing for the Tories, if for no other reason than it was believed that May would not have called for the elections if she felt she could lose. But recently, polls have been tightening between the Tories and the Labour Party and its leader Jeremy Corbyn. Some polls even have the two within striking distance. We wanted to hear more about this, so we called Roger Scully. He's a political science professor at Cardiff University in Wales, and he started by telling us why May started out with an overwhelming lead.

ROGER SCULLY: I think there are two reasons why Theresa May started this election as a strong favorite. The first is that she became prime minister just a year ago. She's enjoyed something of a honeymoon period with the voters. She hadn't made any obvious major public mistakes. The other reason was the weakness of the Labour Party.

Leader Jeremy Corbyn who was elected in the fall of 2015 has not been popular with many people in his own party. And it's pretty much the iron law of British Elections that divided parties do not win general elections. One further thing, though, at the start of the campaign really seemed to cement her position - she focused the election on the issue of Brexit, Britain leaving the European Union. So an election focused around Brexit, where Theresa May and her party were much more trusted than the opposition party seemed an absolutely sure bet for a clear maybe even overwhelming conservative victory.

MARTIN: But then we see that the prime minister's actually been slipping in the polls, and the Labour Party against all odds and expectation has actually been showing some strength in recent weeks. Why is that?

SCULLY: Well the first week or two of the election campaign, it seemed as if the only question was whether Theresa May and the conservatives were going to win big or win very, very big. But in the last month or so, things are gradually starting to go a bit wrong for the conservatives. Theresa May has seemed awkward on the campaign trail.

When she's been given interviews with experienced political journalists, she struggled to answer unscripted questions. The conservative party platform or manifesto, as we call it here, included some unpopular commitments on social care, the long-term care of the elderly and the conservatives were forced into a very quick reversal of their policy on social care. But, secondly, Corbyn has actually surprised a lot of people. He's proven to be rather more adept on the campaign trail than many people expected. And so a bit like Bernie Sanders and the race for the Democratic nomination, this left wing had been written off by many people has actually turned out to be a much harder opponent to defeat than almost everyone had expected.

MARTIN: You know, obviously it's a difficult thing to try to assess how this latest terrorist attack over the weekend will affect people going to vote this coming week. Do you have any sense just from either your own reporting, the polling or history how voters are likely to react given this latest development?

SCULLY: Well, just as in the United States the parties of the center right and conservative parties have historically been more highly evaluated as the best parties to deal with defense and security issues, so you would expect that maybe these latest events if they're going to have any sort of electoral effect help the conservatives.

But the have again here being cantor arguments against the conservatives. One of the things that the conservatives have been doing in recent years is cutting government spending. That has included significant cuts to spending on things like policing, as some aspects of the security services. And the leader of the opposition Jeremy Corbyn and some of the opposition parties have been attacking the conservatives saying that one of the things that they've done by cutting funding for the police, cutting funding for the security services is make Britain more vulnerable. So it's not entirely clear that even these terrorist attacks will necessarily play into the conservatives' perceived long-term advantage on security issues.

MARTIN: That's Roger Scully. He's a professor of political science at Cardiff University in Wales. We're talking about the upcoming elections. They are Thursday, and he was kind enough to speak to us via Skype. Professor Scully, thank you so much for speaking with us.

SCULLY: Thanks a lot. Goodbye. Transcript provided by NPR, Copyright NPR.