What's next for the GOP Obamacare replacement?

The House Budget Committee will be the third congressional panel to mark up the legislation proposed by House Republicans to repeal and replace Obamacare.

The committee is expected to take up the measure next Wednesday, following the  two markups this week by the House Ways and Means Committee and House Energy and Commerce Committee, which advanced the bill.

Rather than being substantive, the Budget panel’s work will be much more narrow and technical next week -- members cannot make a lot of changes. They will take the two measures reported out of the other committees and blend them into one.

House GOP leaders are aiming to have the legislation on the floor by the week of March 20. Members of leadership have said they’re confident it will pass the lower chamber, but the math might not work out in their favor. A number of conservatives, especially within the House Freedom Caucus, have either come out against the measure or have expressed concerns. Democrats, for their part, could unanimously oppose the bill in an effort to protect Obamacare.

Based on the current party breakdown in the House, Speaker Paul Ryan, R-Wisconsin, can lose up to 21 members of the House GOP conference and still pass the bill. If he loses 22 members, however, and doesn’t pick up any Democratic support, the bill would be tied and would fail.

It also faces hurdles in the Senate. Sen. Rand Paul, R-Kentucky, for example, is one of a number of conservatives who have been describing the measure as “Obamacare lite” and Sen. Tom Cotton, R-Arkansas, suggested that House Republicans press pause on the process and start over completely.

Conservative groups were also quick to oppose the bill, including Heritage Action, Americans for Prosperity, Freedom Action and Club for Growth, because they say the Republican bill does not go far enough to repeal the ACA.

Major health advocacy groups that played an influential role in the passage of Obamacare have also come out against the legislation, including the American Medical Association, AARP, American Nurses Association and American Hospital Association.

CBS News’ Catherine Reynolds and Walt Cronkite contributed to this report.