After President Obama unveiled the American Jobs Act, I wrote that his greatest obstacle would be the “centrist” and conservative Democrats who plagued the first two years of his term. Already, Democrats like Florida Senator Bill Nelson and Nebraska Senator Ben Nelson had voiced their “concerns” over the bill, siding over Republicans on the need for deficit reduction above all else.

With the Senate set to vote on the Jobs Act, it seems that this prediction has come to pass. As Erik Wasson reports for The Hill, centrist Democrats have rebelled on the issue of higher taxes on millionaires, even as large majorities of Americans (including Republicans) endorse the proposal. In particular, senators Joe Manchin of West Virginia, Jon Tester of Montana and Ben Nelson all plan to vote against the bill, for fear that it will harm their re-election chances next year.

With unanimous opposition from House Republicans, there was no chance that the American Jobs Act would ever pass. But as a political move, it was supposed to draw an important contrast with the GOP, and demonstrate the extent to which Republican obstruction has blocked federal action on jobs. To that end, it’s important for Democrats to show unity. Wasson quotes a former communications director to former Republican Speaker Dennis Hastert, who notes that if there are substantial Democratic defections, “Republicans will be able to point out in the media that this plan hasn’t got enough support on either side of the aisle and argue it wasn’t thought through.”

When you consider the broad popularity of the American Jobs Act, not only are centrist Democrats harming the party writ large with their cowardice, they’re harming themselves as well. Of course, given the last two years of pointless obstruction from senators like Ben Nelson, it doesn’t come as a surprise that they’d take this route.