“Barack Obama … 96 percent of his votes have been solely along party line.”

In the vice presidential debate in St. Louis, Republican Gov. Sarah Palin tried to take a hammer to Democratic presidential nominee Barack Obama’s postpartisan campaign tack.

“Now, Barack Obama, of course, he’s pretty much only voted along his party lines. In fact, 96 percent of his votes have been solely along party line,” Palin said, questioning whether he could reduce polarization in Washington.

In fact, Obama — who joined the Senate in 2005 — has voted with his party 96 percent of the time, according to a study by

Congressional Quarterly

. CQ’s calculation of party unity measures how often members vote with their party on bills where the parties split. By comparison, rival Sen. John McCain has voted with his fellow Republicans at an 81 percent clip over the entire Bush presidency.

But as PolitiFact has reported

before

, voting studies can be skewed depending on a lot of factors, such as attendance, the roll-call votes picked and the issues that arise during the course of the year. Some congressional sessions may have more head-to-head party line votes than others.

Examining votes that matched the position of President Bush — the titular head of the GOP — shows McCain has supported him 90 percent of the time, while Obama has gone along 40 percent, CQ found.

But the question here is if it’s true that Obama voted along party lines 96 percent of the time, and that claim is True.