Fresh off launching television ads in Wisconsin targeting Sen. Russ Feingold (D), the Progressive Change Campaign Committee has set its sights on Independent Sen. Bernie Sanders of Vermont as the liberal group moves to pressure Congress into including the public insurance option in the final health care reform package.

The PCCC announced Wednesday it was hitting Sanders with 10,000 robocalls per day urging voters to demand that the Senator withhold his vote for any bill that does not include a public insurance option. On Tuesday, the PCCC launched television ads with a similar message in Wisconsin’s three largest television markets aimed at pressuring Feingold. Sanders is a strong supporter of the public option and in fact advocates that the U.S. implement a government-run, single-payer health care system.

However, Sanders, who caucuses with the Democrats, voted with the majority on Christmas Eve to support a health care reform bill that does not include a public insurance option. Senate Majority Leader Harry Reid (D-Nev.) dropped the proposal from the $871 billion package after moderate Democrats threatened to withhold their support for the bill.

The robocalls are scheduled to target voters throughout Vermont over the next two weeks. The text of the call, recorded by a political activist, reads:

“Hi, I’m AJ Van Tassel-Sweet from Northfield, Vermont — calling with the Progressive Change Campaign Committee. I supported Senator Bernie Sanders in the past because I thought he would fight for us. But now the Senate is planning to pass a health care bill without the public health insurance option that most Americans support. Instead, it just mandates that people buy insurance from big insurance companies. That’s not reform, that’s a corporate giveaway. We need a hero right now who will stand up to Joe Lieberman and the insurance industry. If you think Senator Sanders should be that hero, and promise to block any bill without a public option, press one on your keypad. If you disagree, press two.—

Sen. Joe Lieberman (ID-Conn.) vowed to filibuster any bill that included a public insurance option of any kind, although he was not the only moderate member of the majority Conference who was troubled by the proposal.

Meanwhile, negotiations to reconcile the House and Senate health care reform bills are set to get under way next month, although low-level discussions began earlier this week.

Activists who favor the public insurance option — which is a part of the $1.2 trillion House package — are hoping to see it included in the final, negotiated bill, which will need to be approved by both chambers before heading to President Barack Obama’s desk.