Election: Theresa May urges voters to 'strengthen my hand'
Every single vote will count in the June general election, the prime minister has told party workers on a campaign visit to Wales.
Theresa May visited Bridgend as an opinion poll suggested the Tories were set to make gains in Labour heartlands.
The PM said she was "not complacent" adding polls had been wrong before, while Labour called the visit a stunt.
Backing the Tories would "strengthen my hand" in Brexit negotiations and be a vote for a "stronger Wales", she added.
Mrs May claimed a vote for any other party would be for a "weak and failing Jeremy Corbyn propped up by a coalition of chaos".
The prime minister said there was a "very real example here in Wales of Plaid Cymru working with Labour".
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"This is an election where every single vote counts, and every single vote for me and Conservative candidates will be a vote that strengthens my hand in the negotiations for Brexit," she said.
"Give me a mandate to lead Britain, give me a mandate to speak for Britain," she added. "Give me a mandate to deliver for Britain."
Mrs May attacked the Labour Welsh Government's record on health, saying: "If you want to see what Labour want to do to the NHS, just look at the problems here."
Earlier, in an article for the Western Mail, the prime minister said the election was an opportunity to give the UK "the strong and stable leadership it needs to see us through Brexit and beyond".
She accused rival parties of "seeking to disrupt our negotiations, even as 27 other European countries line up to oppose us".
Welsh Labour leader and First Minister Carwyn Jones called the decision of Mrs May, who was shown around a factory in Newport earlier, to visit Labour heartlands in Wales a "stunt".
"But what's important is that people see the Tories for what they are, their idea of leadership is to say nothing and do nothing," he told BBC Wales.
"What we want is to offer hope," he said, "to say to people it doesn't have to be this way."
Labour's UK leader Jeremy Corbyn has already insisted there will be "no deals with the SNP or anybody else".
'Weak and divided'
Hywel Williams, Plaid Cymru's parliamentary leader, said his party would not allow "another deliberate destruction of Welsh industry and for the future of generations of young people to be blighted".
He said: "Unbearable poverty continues to exist where economic activity once thrived and Plaid Cymru will not sit on its hands and allow history to be repeated
"The Tories will win this election. The weak and divided Labour Party are not fit to form a government so what this election is about is sending the strongest people to Westminster to stand up to the Tories and defend Wales."
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Mr Williams added: "Plaid Cymru is the only party that will stand up in Westminster and make sure that the government's actions work for Wales, not just for the south east of England."
Welsh Liberal Democrat leader Mark Williams said: "A hard Brexit will mean real pain for people across Wales, and the reality is already starting to bite through jobs lost and a squeeze to living standards.
"This election is a chance to change the direction of the country and prevent a hard Brexit."
Analysis by Vaughan Roderick, BBC Welsh affairs editor
While all Conservative leaders make a point of including Wales in their election campaign tours, Theresa May's decision to come so early in the battle suggest that she senses that Labour could be vulnerable in some normally safe seats - a suspicion that will have been strengthened by recent polling.
Breaking Labour's grip on one of its historic heartlands would be a major prize for the Conservatives, and the party is likely to pay greater attention to Wales than it has in past elections with resources being targeted on seats that the party would normally regard as lost causes.
A string of seats along the M4 corridor and a cluster of Labour seats in north east Wales could prove to be the key Welsh battlegrounds in this election.
Defeat for Labour would be a bitter blow, severely weakening Carwyn Jones's hand in the upcoming negotiations over the impact of Brexit on Wales.
Labour meanwhile is hoping that its "Welsh Labour" brand will offer some insulation from the UK party's troubles as it struggles to stem a possible blue tide sweeping through some former strongholds.