(Politico)- Senate Democrats including typically mild-mannered Bill Nelson of Florida lit into President Barack Obama during an unusually tense air-clearing caucus session on Thursday, senators and staffers told POLITICO. Nelson told colleagues Obamas unpopularity has become a serious liability for Democrats in his state and blamed the president for creating a toxic political environment for Democrats nationwide, according to two Democrats familiar with his remarks. It was a raucous caucus, said one Democratic senator, who spoke on condition of anonymity because closed-door sessions are not supposed to be discussed with outsiders. Nelson declined to respond when asked about the incident Thursday night, saying he was in a hurry to leave the Capitol to catch a flight. His spokesman didnt return a request for comment. In interviews after the marathon three hour meeting, several senators and senior aides told POLITICO that Nelson was just one of several senators to express anger at White House missteps and air deep concerns about their own political fates if Obama and the Democratic Party leadership cant turn things around by 2012. Added one veteran senator: It was the most frank exchange of views Ive ever seen. Several senators expressed the opinion that Obama needed to show more passion, while party liberals renewed their complaint that Obama should abandon the pretense of bipartisanship in the face of Minority Leader Mitch McConnells intransigence and what they consider the Kentucky Republicans blatantly political tactics aimed at making Obama a one-term president.