PHOENIX -- A bipartisan debate watch party became a proxy battleground for the campaigns of Sens. John McCain (R-Phoenix) and Barack Obama (D-Ill.), as tempers flared and representatives of the state's major parties spun their candidates' performances.

The event at Tom's Tavern in downtown Phoenix was billed as bipartisan, but the decision by the Arizona Republican Party to make it the official debate watch for its supporters resulted in a crowd that was heavily biased toward the Republican presidential nominee. McCain banners, buttons and handmade signs were in evidence throughout the room, making the near absence of representation for Obama all the more conspicuous.

Yet the senator from Illinois was cheered loudly by those in his contingent, at times drowning out the enthusiasm of McCain voters. Jeers and derisive comments toward the candidates - and their backers in the room - emerged frequently as well from both sides.

The atmosphere was charged as the debate ended and the event moved into its second phase: responses from the parties.

Randy Pullen, who chairs the Arizona Republicans, said it was a great debate compared with those of the past few cycles, but said Obama was on the defensive most of the night. Pullen further said that McCain's experience in foreign policy was evident, while Obama didn't demonstrate a similar mastery of the topic.

"It's the classic example of a show horse versus a workhorse," Pullen said.

Emily DeRose, the Arizona Democratic Party's communications director, shot back that Obama displayed judgment on the issues, which McCain did not.

DeRose met a volley of boos when she said McCain had shown "some of the most erratic behavior of any candidate of all time" during the past week, and said over the crowd, "We can agree without being disagreeable."