The recent terrorist attacks in Manchester and London have cast a shadow over the upcoming parliamentary election on Thursday in the United Kingdom.

According to a YouGov poll a month ago, the major issues on British voters' minds were Brexit, the economy, healthcare, and immigration. National security issues didn't even register.

Obviously, that's now changed. A poll released after the Manchester attacks but prior to the London attacks suggests terrorism is now the second-highest voter concern. We can safely assume terrorism concerns are now even more significant after Saturday. Anecdotal evidence attests to this. British streets are more quiet: people are resolute but scared.

So what does this mean for Thursday's election?

Put simply, I believe incumbent Prime Minister Theresa May of the Conservative Party will benefit.

May has electorally valuable experience. Between 2010 and 2016, May was the Home Secretary (the government minister responsible for domestic counter-terrorism) under former Prime Minister David Cameron. She was seen as a safe pair of hands.

As prime minister, May has extended these popular perceptions. Prior to the recent attacks, May was pushing for new intelligence powers to access encrypted communication apps (such as Telegram and WhatsApp) and to record Brits' Internet histories. Once unpopular, those policies now seem prudent to many voters.

In essence, May's offer of greater security in return for increased government power is increasingly tempting.

Labour Party leader Jeremy Corbyn is a very different politician.

Prior to the attacks, Corbyn was renowned as a leading critic of British security services. In 2015, when asked whether as prime minister he would authorize the police to ''shoot-to-kill'' suicide bombers, Corbyn stated, ''I'm not happy with a shoot to kill policy in general.''

That reaction played very badly at the time, but now it seems astonishingly short-sighted -- the reason more people were not killed in London on Saturday was the response of armed police officers.

Corbyn has a broader problem here: his long-standing record. In 2009, Corbyn praised his ''friends'' from Hamas and the Lebanese Hezbollah as he invited them to speak in parliament. Just as problematic, Corbyn still specifically opposes military action against the Islamic State (including strikes against Islamic State leaders plotting attacks on the U.K.).

For an electorate seeking action against terrorists, Corbyn doesn't fit the bill.

That said, May is lucky. As Home Secretary, she presided over cuts to police forces across the U.K. And while armed police are the only realistic means of defeating terrorist attackers, those cuts would be a strong line of argument for a more moderate Labour leader. Just not for Corbyn. And in the end, Corbyn is why May benefits most from these attacks. Though her approval ratings have fallen, the most recent polls show May remains more popular than Corbyn by 15 to 18 percentage points.

For a public in fear, perceptions of a leader's strength make all the difference.