Deputy Liberal Democrat leader Simon Hughes has admitted exchanging text messages with Labour's Ed Miliband.
Mr Hughes said it was a sign of "sensible, grown up politics" to talk to politicians from other parties.
His comments come after Business Secretary Vince Cable said he had sent texts to Labour leader Mr Miliband and shadow chancellor Ed Balls said he could work with the Lib Dem Cabinet minister on measures to boost the economy.
Mr Hughes said: "I've had text messages with Ed Miliband, I have his number on my phone.
"In sensible, grown up politics you talk to people about how you get the best deal for Britain.
"I have talked to Tories and Labour people all my life in Parliament.
"I think people often say why don't you work together, and sometimes working together is a very good thing."
Labour's deputy leader Harriet Harman has rejected suggestions that the party should be wooing the Liberal Democrats to pave the way for a coalition after the next election, insisting there will be "no cosying up" to Nick Clegg's party.