Timmermans met with Bulgaria's prime minister Boyko Borissov to gather support for the his bid for the EU's top job - but what would usually be a private meeting, was broadcast live on Facebook.
An EU summit in Brussels has stretched into Monday morning as leaders continue their debate on who should take the European Commission presidency.
Frans Timmermans, the socialist candidate, appears to be growing as a compromise choice - an idea put forward by German Chancellor Angela Merkel following lack lustre support for the European People's Party's (EPP) Manfred Weber.
In a bid to boost support for his claim, Timmermans met Bulgarian Prime Minister Boyko Borissov - an EPP member himself - for a chat during the summit.
But unlike similar manoeuvring meetings in the political sphere that are usually held in private, this one was broadcast, in part, live to the Bulgarian leader's Facebook.
In the video, the pair greeted each other with a friendly embrace, while Borissov noted the "compromise" that "is on the horizon".
"Weber will take the Parliament and you will take the Commission, so I wanted to see from you," Borissov said, suggesting he would be open to the socialist taking the role.
Borissov then laid out a list of ideas important to Bulgaria, including joining the borderless Schengen zone, and the creation of an EU-led programme that could help end Bulgaria's problems with corruption.
"There are some EU member states in Central and Eastern Europe that have some concerns but I told them that I believe in your integrity," the Bulgarian leader then assured the Dutchman.
He appeared to refer to countries who have expressed reservations in a Timmermans lead, such as Poland, which says he "divides Europe", and "does not understand Europe that is emerging from a post-communist collapse."
Back in the meeting, Timmermans is seen briefly addressing Borissov and their good working relationship.
But before going further, Timmermans turns to the camera livestreaming the meeting and suggests: "I’m not sure we should be recording all of this," before it cuts a short second later.