Scottish Labour has announced its first candidates for June's snap election, including a former MSP and the head of the Better Together campaign.
Blair McDougall, who was campaign director for the pro-Union side in 2014, is standing in East Renfrewshire.
And former MSP Cara Hilton is standing in Dunfermline and West Fife.
All sitting SNP MPs are to defend their seats, while a number of Conservative MSPs have put themselves forward.
Meanwhile, the Lib Dems are expected to select their candidate for target seat Edinburgh West on Friday.
Mr McDougall is taking on the SNP's Kirsten Oswald, who won East Renfrewshire by a margin of 3,718 votes, a 6.6% majority, in 2015 - beating then-Scottish Labour leader Jim Murphy.
In the 2014 independence referendum, East Renfrewshire voted No by a margin of 63.19% on a turnout of 90.46%.
Mr McDougall said it was "ridiculous that one of the most pro-Union constituencies in the country is represented by an SNP MP".
He added: "I brought together the anti-independence majority in 2014 and I'm going to do the same on 8 June."
Ms Oswald said what Scotland needed was "a strong SNP voice in Westminster" to stand against "an increasingly right-wing Tory government".
She said: "It has been a privilege to represent my home area for the past two years, and I am happy to stand on my record in the contest ahead."
The Scottish Conservatives, meanwhile, have selected Paul Masterton as their candidate for the seat. The party took the equivalent Holyrood constituency of Eastwood in 2016 in a three-way contest with Labour and the SNP.
Ms Hilton was MSP for Dunfermline from 2013 to 2016, when she lost the seat to the SNP's Shirley-Anne Somerville.
She is now contesting the corresponding Westminster constituency, Dunfermline and Fife West, which was taken by the SNP's Douglas Chapman in 2015 by more than 10,000 votes, a majority of 18.5%.
She said: "As a former by-election winner, I know how to defeat the SNP in Fife and I am determined to do so again. SNP and Tory cuts have devastated local services in Fife, despite the best efforts of our Labour-run council."
Mr Chapman said he intends to lead the SNP campaign "from the front".
He said: "I am keen to finish the job I've started and I seek the support of the people of this constituency to see the job through - only the SNP can be trusted to stand up for Scotland."
Scotland's parties are going through an accelerated process of selecting candidates for June's snap election.
The SNP is seeking five candidates, one for each of the three seats they failed to win in 2015 and replacements for Michelle Thomson and Natalie McGarry, who are both stepping down from parliament as independent members following separate police investigations.
The other three incumbent members - Labour's Ian Murray, Tory Scottish Secretary David Mundell, and Lib Dem Alistair Carmichael - are all defending their seats.
Conservative MSP John Lamont has resigned his Holyrood constituency seat to fight for the Berwickshire, Roxburgh and Selkirk seat at Westminster.
His Tory colleagues Douglas Ross, Ross Thomson and Miles Briggs are all also standing in June's election, targeting seats in Moray, Aberdeen South and Edinburgh South West respectively.
The Lib Dems are operating all-female shortlists for a number of target seats, such as Edinburgh West. Christine Jardine, a former UK government special advisor who ran for the Lib Dems in Aberdeenshire in 2015 and 2016, is among the favourites for that seat.
Former MP Jo Swinson has already come forward in a bid to re-take East Dunbartonshire from the SNP's John Nicolson.