Willie Rennie believes the Lib Dems are on course to claim an SNP ministerial scalp by winning their “top target” seat in the Highlands.
The party leader said candidate Molly Nolan had a “great chance” of defeating Children’s Minister Maree Todd in Caithness, Sutherland and Ross.
He said the Lib Dems were making “quite a lot of inroads” in the seat, which was previously held by the SNP’s Gail Ross, and that it was “looking very positive”.
Ms Ross, who has stepped down, won the seat with a 3,913 majority in 2016, but Jamie Stone reclaimed the Westminster version of the constituency for the Lib Dems in 2017, and then held it in 2019.
Mr Rennie indicated that it was now considered to be the party’s best chance of gaining a constituency at the upcoming election.
Ms Todd was the SNP’s only regional list MSP in the Highlands and Islands in the last parliament, but she is third on the party’s list at this election, meaning defeat in the constituency could end her Holyrood career.
Speaking to journalists as the Lib Dem manifesto was launched, Mr Rennie said: “Caithness is certainly the most marginal.
“We won Jamie’s seat by quite a tight margin last time around. We won it 2017 and 2019.
“So that is our top target. Great young candidate, bright, really intelligent, and is making quite a lot of inroads.
“So that is possible. The other ones – of course, there is Skye, Lochaber, there is Aberdeenshire East and West – there is quite a lot of effort going into those seats.
“We will campaign, build up more momentum and there’s a chance, but our top target just now, there is no doubt, is Caithness.
“Of course we are looking at list seats as well, because it’s a mixture of the two. But yes, we are optimistic we can gain that, but we never set upper limits on what we can achieve.”
Mr Rennie added that victory in seats such as Caithness, Sutherland and Ross could represent “the difference” between the SNP winning a majority or falling short.
The party leader, who has been in the post for a decade, also vowed to continue in the role throughout the next parliament.
“I love this job. I’m not moving. This is too good. To be able to influence things through this time is a special privilege,” he said.
An SNP spokesperson said: “Unlike the Lib Dems, who have form for making big boasts and then falling flat on their face, the SNP take absolutely nothing for granted.
“We remain focused on returning as many MSPs as possible across the Highlands, and the rest of the country, come May 6.
“And unlike Willie Rennie’s party, who are now effectively pro-Brexit, the SNP are the only party offering Scotland a route back into the European Union – something the people of Caithness, Sutherland and Ross voted to remain part of in 2016.
“Only both votes SNP on 6 May can put Scotland’s future in Scotland’s hands.”