General Electric has reached a tentative agreement with the French media conglomerate Vivendi that clears the way for the sale of NBC Universal, including the flagship NBC network, to Comcast, the nation’s largest cable operator, people briefed on the deal said Monday.

Under terms of the deal, G.E. will buy Vivendi’s 20 percent stake in NBC Universal for about $5.8 billion. It removes one of the few remaining hurdles in its plan to sell control of the television and movie company to Comcast in a $30 billion agreement that reflects the changing landscape of broadcast television.

While a deal between G.E. and Comcast still could hit a snag over the final price, it is considered highly likely: G.E. wants to sell NBC because of rising losses, and Comcast wants to buy it to control more of the television programs and movies that flow through its cable systems.

The final threads may take days to sew up and there is a tentative plan to announce a final deal on Thursday, according to these people, who spoke on condition of anonymity because the negotiations are not complete.