Democrats and their allies are ramping up the pressure on the Senate’s newest Member, Scott Brown (R), as he prepares to cast his first votes on legislation.

The latest: a television ad from the progressive, labor-backed advocacy group Americans United for Change urging Brown to support the Democrats’ jobs bill.

The 30-second spot, which is running on cable news stations in Boston, reminds viewers of Brown’s promise during his special election campaign that he is “nobody’s Senator but yours,” not beholden to either party or special interests.

The ad ran Monday, will run again today and is costing the group a little more than $13,000.

The Democratic National Committee went after Brown hard last week for claiming the stimulus bill has not created “any new jobs” in Massachusetts and pointed out that he touted federal funding that the state received via the bill as recently as October.