Watch the PM's full interview with Robert Peston above
Prime Minister Theresa May has denied putting her party before her country in calling for an early election, telling ITV News: "I'm asking the British people to put their trust in me."
In an exclusive interview, Mrs May told Political Editor Robert Peston she decided on her surprise election U-turn while walking in Wales with her husband Philip shortly before Easter.
She said she was not "playing political games" in calling for a vote amid commanding opinion poll ratings but much international and domestic instability.
"This is about what's in the best long-term national interest for the country," she said.
Mrs May said "times have changed" since the 2015 manifesto and said "we need to now look for a different future".
Video above: May on how "times have changed" since the 2015 election
After frequent denials of a snap election, Mrs May told Peston she started to change her mind during the early stage of the Brexit process before making her decision to call for a June 8 vote while away.
"As we were going through the Article 50 process the opposition ... potential attempts to jeopardise or frustrate the process in the future became clearer.
"And then before Easter I spent a few days walking in Wales with my husband (when) I thought about this long and hard.
Video above: Theresa May on her walking holiday decision
"I came to the decision that to provide that certainty and stability for the future that this was the way to do it - to have an election."
Mrs May said the national vote was a matter of trust.
"I trust the British people," she said. "The British people gave the government a job to do in terms of coming out of the European Union. I'm going to be asking the British people to put their trust in me."
The prime minister said she would be "unashamedly" urging voters to retain Britain's "very precious union" on the campaign trail amid the renewed efforts for Scotland to break away.
Mrs May had scolded Scotland's First Minister Nicola Sturgeon for playing "games" by calling for a second Scottish referendum last month at a time when the PM continued to rule out an early national vote.
But she told Peston her shock call for an early election was not a Westminster power play as she accused the opposition parties of political gamesmanship around Brexit.
"Politics is not a game and the problem is we have other parties who are playing games," she said.
"The games that are being played by other parties jeopardise our ability to prepare for Brexit here at home and weaken our negotiations with Europe."