When Murdoch signed onto Twitter at the beginning of January, it quickly became apparent he would use the microblogging tool to freely share his opinions. He tweeted favorably several times about Rick Santorum, before Santorum dropped out of the race for the Republican nomination.

Last weekend, the influential News Corp. owner tweeted that Romney so far fails to “look like a challenger,” and suggested he had evaded offering specific solutions on the topic of immigration.

On Sunday, apparently after meeting the GOP’s White House hopeful in person, Murdoch posted a tweet calling on Romney to drop some “old friends” from his staff and hire “real pros” to help him defeat President Obama in the November general election.

On Monday, Murdoch also charged that the Romney people were “upset at me,” apparently over his criticism. The Romney campaign did not respond when asked to comment on Murdoch’s claim.