A liberal group went on the offensive against new Sen. Scott Brown (R-Mass.) on Monday, seeking to pressure him into supporting a jobs bill before the Senate.

Americans United for Change released a television ad in the Boston area this morning featuring clips of Brown stressing his independence, saying that the newly-sworn-in senator should keep that promise by independence by voting for the $15 billion jobs bill facing a procedural vote today.

The ad follows a formula that many groups may pursue against Brown over the next two years, until he has to seek reelection in 2012. Having scored an unlikely Republican victory in heavily-Democratic Massachusetts, Brown is seen as a possible supporter of some Democratic priorities as a way to burnish his centrist credentials. 

"Today, Sen. Brown will have his chance to cast an important vote on legislation that would put Americans back to work," said Americans United for Change acting executive director Tom McMahon. "Will Sen. Brown buck his GOP leaders that have been huddling with lobbyists to block the bill or will he show his independence and vote to put the people of Massachusetts back to work?”

Senate Majority Leader Harry Reid (D-Nev.) said this weekend that there's a good chance Brown will support the jobs bill, while Senate Minority Leader Mitch McConnell (R-Ky.) said that many Republicans -- not just brown -- "may well" support the package.

Watch a video of the ad below: