Theresa May and Ruth Davidson have made a pledge to stand up to the Scottish National Party at the launch of the Scottish Conservatives' manifesto.
They were speaking at an event in Edinburgh.
Scottish party leader Ms Davidson told the gathering that the election on 8 June was about "bringing the SNP down to size".
Prime minister Mrs May said the Conservatives were the "only party" able to stand up to the SNP.
Ms Davidson set out her proposals 24 hours after the launch of the UK Conservative manifesto.
The Tories are hopeful of gains in next month's election, having made significant progress in May's local elections. The party won just one seat in the 2015 general election.
- Election campaign latest
- Key points in Scottish Conservative manifesto
Scotland's main opposition parties criticised the Conservatives about their stance on the constitution, Brexit and Scottish independence.
The SNP, Scottish Labour and the Scottish Liberal Democrats are expected to launch their manifestos next week.
Mrs May began her address by saying the election was defined by "one question, and one question only - who can lead us through Brexit and get a deal that works for the whole of UK?".
She explained: "This manifesto is my plan for a stronger union and a better Britain. My plan to build a country that works for everyone, not just a privileged few."
The politician said there were challenges ahead but she believed she had a "credible, deliverable programme for government around which the whole country can unite".
Mrs May added: "Unlike the offerings of other parties, we are being upfront and honest with the British people about the scale of the task we face.
"Because leadership means being straight with people about the challenges ahead and the hard work required to overcome them."
She went on to attack the SNP, accusing the party of letting Scotland's young people down because of its "tunnel-vision obsession with independence".
Page 34 of the Scottish manifesto said that "now was not the time" for another referendum and that in order for one to be be held;
- the Brexit process needed to be "played out"
- and it should not take place "unless there is public consent for it to happen".
The Scottish Conservatives pitch themselves as the chief defenders of the Union, campaigning fairly squarely on their opposition to a second independence referendum.
So much of the attention at their manifesto launch was on the small section of the document relating to that, which features a sort of "double lock".
The manifesto says there should not be a referendum until the Brexit has "played out", and that there must be "public consent".
What does this mean? Theresa May twice declined to go into specifics in the Q&A, and the picture drawn by other politicians still features some grey areas.
The first part is reasonably simple - Brexit will have "played out" once the process of leaving the EU is complete, and any associated devolution to Holyrood has bedded in.
On public consent, the Tories insist it is a matter of "principle". They cite the 2012 agreement for the first indyref as a "gold standard", but don't want to link this to any dates or elections.
Essentially, they see the onus as being on the SNP and the pro-independence side to prove that there is appetite, or "public consent", for a new referendum.
'Get back to the day job'
Ms Davidson said the Scottish Conservatives were "back in the centre ground of Scottish politics".
She insisted that her party had the "ideas and plan" to turn "our faltering education system" around, to "champion" the fair work agenda and to "invest" in the next generation of family homes.
Ms Davidson added: "And, at this election, we are offering to do something else too.
"And that is to send the SNP a clear and unequivocal message - no to their unwanted plan for another referendum on independence.
"Enough of the endless division and uncertainty they have imposed on our country - it is time for them to get back to the day job. And it is time for the country to come back together.
"It is time to work with family, friends and neighbours across the UK to boost our security and our prosperity. We know Nicola Sturgeon doesn't want to hear that. So at this election we say this: let's bring the SNP down to size, to make her listen."
Key points from the Scottish Conservative manifesto
- In education the manifesto says there should be a review of the national curriculum in Scottish schools - Curriculum for Excellence.
- On energy, the party says it would give "support" to the shale gas industry in Scotland.
- In local government, the document backs the idea of directly elected "provosts for cities, councils or regions in Scotland who could drive economic policy".
- On tax, it would "press the Scottish government to raise the threshold for the higher rate of income tax to £50,000.
- In the field of transport the party supports a "Road Maintenance Fund in Scotland, inviting local authorities to bid for money to fix potholes".
- On welfare, the Conservatives want to protect universal Winter Fuel Payments for all older people, with no means-testing in Scotland, unlike the policy for England.
- And the party wants to see 100,000 homes built in Scotland over the next five years.
What are opposition parties saying?
Former first minister Alex Salmond accused the Tories of being "mired in complete and utter confusion" over the constitution.
He said: "There is already a cast-iron democratic mandate for Scotland to have a choice, based on last year's Holyrood election and the subsequent vote of the Scottish Parliament.
"The Tories want to deny and to block that mandate, but they haven't the got the guts or the gumption to say how. That lack of clarity betrays the weakness of their position - they know that their behaviour is antidemocratic and that it will not hold."
leader Kezia Dugdale said the Conservatives were to blame for any constitutional turmoil.
He said: "It is the Tories' reckless Brexit gamble that has given the SNP the excuse it has been looking for to try to force another divisive independence referendum.
"Rather than fix the problems they have created in our country, the Conservatives are intent on continuing to divide our country and increase the risk of a second independence referendum."
leader Willie Rennie also attacked the Tories over Brexit.
He said: "Their cuts to pensions, social care and free school meals shows that the Conservative Party is mean spirited and cold hearted. It is lurching to the right to capture votes from UKIP.
"The Conservative-UKIP pursuit of a damaging hard Brexit will be damaging to our security, jobs and the NHS."