The prime minister and the leader of the opposition refused to join TV debates, making the election result seem more of a foregone conclusion than ever.
Scotland's First Minister has warned another independence vote may be "inevitable."
Prime Minister May told Scotland she believed "with all my heart" in keeping the U.K. together.
Nicola Sturgeon was pressed to work closely with the U.K. government.
Only 40 of Labour's 229 MPs back the party's leaderJeremy Corbyn
Scotland's first minister warns that an EU exit would lead to a right-wing power grab.
Research shows Scotland's support for the EU is far from secure.
The former Scottish first minister also urged the "Remain" campaign to be less "negative."
Scots, who voted against independence in 2014, are more likely to vote to stay in the European Union, polls show.
"I will campaign wholeheartedly to achieve that result," Sturgeon will say.
No other politician ranks in the top 20.
A new survey back up the ruling Scottish National Party's argument.
The door is open to a second referendum on Scottish independence as early as 2020
Nationalists who claims last year's referendum was fixed, intend to ensure their votes are not tampered with
Labour deal with SNP would result in "mayhem" says former Conservative PM as knife-edge election race continues.
Labour leader polls 35% after debating four smaller party leaders, including SNP's Nicola Sturgeon, who got 31%.
The contest comes before an unusually close national election on May 7.
Polls suggest Scottish National Party could form third biggest party in UK Parliament after May 7 election.
Opinion polls show the SNP is set to take dozens of seats from the Labour Party in Scotland.