Vice President Joe Biden set a goal of at least $1 trillion in budget cuts from negotiations with congressional leaders on the federal debt as talks yesterday turned to Medicare, a contentious issue that risks replicating a partisan divide on Capitol Hill. Democrats in the meeting ruled out concessions on Medicare without Republican agreement to raise tax revenue, a step the party's leaders so far have rejected, according to someone familiar with the talks who spoke on condition of anonymity. Biden underscored the issue in remarks to reporters afterward. "I made clear today that revenues have to be in the deal," Biden said, even as he expressed optimism about prospects for the talks. Negotiators are on a pace "to get above $1 trillion" in cuts for a "down payment on the process," he said. There is there is no agreement yet, a participant in the talks who wasn't authorized to speak publicly said on condition of anonymity.