Swann told reporters in Calgary that he has been trying to push some sort of agreement with the NDP, the Greens and the Alberta Party for the last few years.
"Unfortunately no other parties have been willing to talk about co-operation until the last six or eight weeks," Swann said Thursday. "Co-operation means trust. We don't have the trust we need to have some solid agreements on co-operation.
"We need to get to the table and talk about co-operation right after this election. We cannot keep dividing the progressive vote in this province."
The issue was raised by Edmonton Liberal Laurie Blakeman when the party was looking for an interim leader in January.
She said she was open to the job, but wanted to work to unite the centre-left to fight the Progressive Conservative government.
The party chose Swann instead.
Blakeman is running for re-election in the Edmonton Centre constituency with the help of two other political parties. The Alberta Party and the Green party have also nominated her as their candidate, but she will be listed on the ballot as a Liberal.
Swann called her move a symbolic gesture that should give all progressive Albertans hope.
The Liberals faced some criticism earlier this week when the party appointed a candidate to run against Alberta Party Leader Greg Clark in Calgary Elbow. Clark finished second in a recent byelection to Education Minister Gordon Dirks by a margin far less than the number of votes the fourth-place Liberals received.
The Alberta Liberals are fighting for their political lives. The party has dipped in the polls and, of the five seats they held when the legislature dissolved, only Swann and Blakeman are seeking re-election.
The party is running candidates in 47 of Alberta's 87 ridings. Swann said there are ridings the Liberals can win and there was a commitment made and resources given to those ridings prior to the election being called.
He acknowledged that uniting parties would not be easy.
"We have been rivals for decades. Even the Alberta Party has been a very fierce rival.
"To expect us to sit down at the table and find a way to co-operate is a little much in the last six weeks before an election."
Follow @BillGraveland on Twitter