Oh, it’s subtle, but Senator Ben Nelson’s new ad that will run in Nebraska makes one clear point to his red-state constituents — he’s not going to be corralled by Nancy Pelosi, Harry Reid, or Barack Obama on health-care reform. Nelson lays out his principles for reform, which include two mentions of cost control and no mention of universal health insurance or public plans. It’s a line in the sand, and it shows the difficulty that Democratic leadership will have in rolling Blue Dogs in either chamber after August’s protests:

Chris Cillizza at The Fix reports on Nelson’s ad campaign (via Jake Tapper):

Criticized by two liberal groups about his approach to President Obama’s health care reform proposal, Nebraska Sen. Ben Nelson is hitting back, evidence of the issue’s potential political peril for the 13 Senate Democrats who represent states carried by Sen. John McCain (Ariz.) in 2008.

After Democracy for America and the Progressive Change Campaign Committee went up with ad hitting Nelson for “leading the charge to delay health reform” and accepting millions in campaign contributions from the insurance industry, Nelson launched his own commercial on Tuesday responding to the charges.

“You’ve probably been hearing a lot about health care reform and like too much stuff that comes out of Washington it’s hard to tell what is fact and what is fiction,” Nelson says in the ad, going on to outline his belief that a bill must keep spending down and aid small businesses. “You can count on me to always put Nebraska first,” says Nelson at the ad’s conclusion.

As the polling shifts overall towards opposition to ObamaCare and especially in Blue Dog constituencies, expect to see more pushback.  Nelson may be a Democrat, but he wants to remain employed (hey, it’s a tough economy out there!), and voters won’t send Nelson or any other Democrat back to Washington except in the most liberal districts and states after approving a bill that is becoming as unpopular as ObamaCare.  As these Representatives and Senators returned, shellshocked, to Washington, that message will be clear.