(CNN) The House passed a bill Thursday afternoon aimed at shoring up protections for those with pre-existing health conditions, part of Democrats' plans for protecting the Affordable Care Act under the Trump administration.

The legislation was approved 230 to 183, mostly along party lines with four Republican members joining Democrats. While it's not expected to be picked up by the Republican-controlled Senate, the vote gives Democrats another messaging tool in the politically divisive fight over health care.

The bill would nullify a Trump administration guidance that would allow states to ask for waivers to make major changes to their Obamacare markets.

The Centers for Medicare & Medicaid Services laid out in November four examples of what states could request -- opening the door for people to use subsidies to buy coverage outside the Obamacare exchanges. This would include short-term health insurance plans that can reject people with pre-existing conditions or charge them higher premiums. The Trump administration last year made these policies more attractive by extending their terms to just under a year, instead of three months.

However, no states have taken the agency up on its offer. Last week, it issued a request for more ideas on waiver concepts and programs states could consider under the so-called State Relief and Empowerment Waiver plan.

Read More