"I expect to support Gov Corbett," Cohen said in an e-mail, without elaborating on his rationale for doing so.
Last month, he and his wife, Rhonda, held a small fund-raiser at their Mount Airy home for Corbett that drew about 30 people, mainly Republicans, but also a few Democrats, and raised about $200,000.
Cohen praised Corbett that evening as a friend, a "man of integrity," and a "good public servant," one attendee said.
Only 19 months earlier, the Cohen residence was the scene of an event that raised $1.2 million for Obama's reelection.
At the time, Obama thanked the Cohens for having been supportive for so many years.
Few who attended the most recent event were surprised that Cohen is now using his clout for Corbett.
They said that as the leader of the nation's biggest cable company, Cohen is a businessman first who recognizes that history has demonstrated that Pennsylvania's incumbent governors do not often lose reelection.
"He's a partisan but pragmatic Democrat," said one corporate executive in Philadelphia, who attended the fund-raiser but would not speak for attribution.
A prominent Philadelphia Republican, who also did not speak for attribution, said Cohen is well aware that the cable industry is regulated by state boards whose members are appointed by the governor.
"Cohen is an extremely loyal guy," he said. "His first client is Comcast, and that does require him to cross the aisle.
Longtime Corbett supporters say Cohen is responding to policies, not party.
"David Cohen is very smart in business and in politics," said Brian Nutt, who managed Corbett's 2010 campaign and now serves as an adviser. "I think he wants what's in the best interest of Pennsylvania, and that is Corbett."
Another longtime Republican Party leader who attended the event said he had quietly supported Democrats in the past based on their accomplishments and thought Cohen was judging Corbett by the same standards.
"It's not about supporting a Republican, it's about supporting the person he thinks has done the best job," said the Republican leader, who did not want to be identified. "That said, I don't think you'll see him on a Tom Corbett float going down Broad Street."
A review of campaign contributions shows Cohen and his wife supporting both Republicans and Democrats over the years, both in Pennsylvania and around the country.
In addition to their fund-raising efforts, the Cohens are among Pennsylvania's most generous personal donors to political campaigns, giving almost $300,000 to candidates and political action committees in 2011-12, according to campaign finance data.
Some of the largest contributions went to PACs to support Obama, but Cohen also chipped in $18,000 last year to help Republican PACs and individual candidates.
At least one prominent Democrat was a bit taken aback by the news.
Rendell said he was surprised that his longtime ally and former mayoral chief of staff would throw his weight behind his Republican successor.
"Hey, he's a free agent," Rendell said in an interview. "He doesn't report to me anymore."
Contact Amy Worden at 717-783-2594 or firstname.lastname@example.org and follow @inkyamy on Twitter.