The string of Westminster meetings continues as the Liberal Democrats and the Conservatives have further discussions at the Cabinet Office.
The fresh talks come after party leaders David Cameron and Nick Clegg met privately for an hour earlier today according to Liberal Democrats sources.
Teams from either party will continue negotiating following the Tories response to calls for clarification on voting reform.
Mr Cameron's party have offered a referendum on scrapping the first-past-the-post system for Westminster elections.
The Lib Dems have been locked in talks with the Labour party this morning.
Labour's Ed Miliband described the three hour meeting as "constructive", but reports in Westminster suggested the Lib Dems remain cautious about a pact.
A Lib-Lab coalition would still not have a Commons majority and would be forced to rely on other, smaller parties as part of a so-called "rainbow" alliance.
Lib Dem leader Nick Clegg said he was "as impatient as anyone else" to resolve the political impasse and said he hoped to make an announcement "as quickly as we possibly can".