WASHINGTON — Speaker Paul D. Ryan said Wednesday that the House would press ahead with a vote on a broad immigration bill that includes language to curb the Trump administration’s practice of separating families on the border.

“We don’t think families should be separated, period,” Mr. Ryan said. “We’ve seen the videos, heard the audio.”

But doubts persisted about the bill’s chances of passage when it comes up for a vote on Thursday, and Senate Republicans were pursuing a different strategy. In that chamber, lawmakers were working to develop narrow legislation that would address the issue of separating families on the border.

For now, at least, Mr. Ryan declined to entertain the possibility of considering a narrower measure aimed at stopping the separation of migrant families.