Theresa May has urged Scots to vote for her to "strengthen the Union", the economy and her hand in Brexit talks.
The call came as she was making her first campaign visit to Scotland ahead of June's snap general election.
In London, Labour's Jeremy Corbyn talked to young people, while the Lib Dem's Tim Farron said he wanted to become the leader of the UK opposition.
In Glasgow, Nicola Sturgeon said the SNP "will not let the Tories drag Scotland backwards".
The UK goes to the polls on 8 June for the general election, five weeks after local authority elections across Scotland, as well as in England and Wales.
Mrs May told a gathering of supporters in Crathes, Aberdeenshire, that she wanted to build a more united nation by "standing up against the separatists who want to break up our country".
Describing the election as the "most important" one in her lifetime, she said: "My message to the people of Scotland is clear - every vote for me and my team will strengthen my hand in the Brexit negotiations.
"That will strengthen the Union, strengthen the economy and the UK and Scotland together will flourish, because if Scotland is flourishing the rest of the United Kingdom is flourishing too.
"That's really important because as prime minister of the United Kingdom, I want to see every part of our country succeed."
Meanwhile, First Minister Ms Sturgeon told party activists at a community education and employment centre in Glasgow that Scotland needed strong SNP MPs at Westminster to keep a check on the Tories.
She set out examples of what she said was the SNP "delivering positive change".
She said: "Here in the East End of Glasgow we don't need to be reminded of what happens when the Tories are in power at Westminster.
"We've seen it over generations and now, even with a small majority, Tory cuts are doing real damage to communities like this one. Every Tory vote risks allowing them to impose deeper cuts, penalise the vulnerable and undermine the Scottish Parliament.
"So in this general election, we have the chance to say loudly and clearly that Scotland will not let the Tories drag Scotland backwards."
Scottish Labour has been campaigning in Edinburgh, while the Lib Dems have been out in Helensburgh and Kirkintilloch.
Both parties restated their opposition to a second independence referendum.
Scottish Labour leader Kezia Dugdale said it was Tory actions which had led to the issue appearing again.
She said: "I think the fact that Theresa May has forced this hard Brexit upon us is exactly why we have the talk about a second independence referendum.
"So I would say to people across the country, if they are opposed to independence and they want people to invest in their public services, the only thing to do is to vote Labour."
Scottish Lib Dem leader Willie Rennie said next week's council elections and the general election were a "big opportunity to say no to independence and to elect a local champion for your community".
He added: "Are they going to have a local champion who is going to stick up for them or are they going to get somebody who is going to cheerlead for independence? I think they want a local champion and that's why they'll vote for the Liberal Democrats."