Strategists believe the U.K. election results point to a clear erosion of Prime Minister Theresa May's political leadership, setting the stage for arduous Brexit negotiations ahead.

With the bulk of seats declared in the General Election, no party has gained a clear majority and the U.K. now faces a hung parliament. Doubts over May's future are now widespread.

"The alarm bells should be ringing ... Her future looks bleak in the party," said Herve Lemahieu, research fellow at the Lowy Institute Institute for International Policy, a Sydney-based think tank. "This (election) is clearly an exercise that backfired on her."

"This election was a very big miscalculation," echoed Andrew Gamble, politics professor at the Universities of Cambridge and Sheffield, adding that May's authority would have weakened even with a Conservative majority outcome.

Speculation as to her resignation is already underway.

"She'll try to stay in the game, but there will be pressure within the party to see her moved. Even if she retains the leadership, she's lost credibility in the eyes of Brussels in the lead-up to the Brexit negotiations, so she's in a far worse position," said Lemahieu.