A key liberal group is making a last-minute ad push this weekend blasting House Republicans' health bill as boosting insurers' profits.

Americans United for Change is spending $17,000 on a new television ad to air on cable stations in the Washington, D.C. area to target lawmakers before a Saturday evening vote on House Democrats' health reform proposal.

But the new ad takes aim at the Republican proposal, which, according to the Congressional Budget Office (CBO), would be significantly less expensive and reduce the deficit by $68 billion, but only expand new coverage to 3 million Americans.

The ad calls the GOP plan the "Health Insurance Profits Protection Act," alleging that the plan would not keep premiums down or guarantee coverage for Americans with preexisting medical conditions.

The ad blitz is specifically targeted at House lawmakers before the Saturday group, a spokesman for Americans United for Change said.

The House is expected to take its landmark vote around 6 p.m. on Saturday, a rare weekend vote.

Watch the new ad below: