WASHINGTON—House Speaker Mike Johnson (R., La.) is headed into a major test on Tuesday with a possible vote on his proposal temporarily extending government funding through early next year, as lawmakers of both parties moved to get legislation to President Biden’s desk ahead of a looming government shutdown this weekend. 

Johnson’s two-step plan would extend government funding at current levels for some federal agencies until mid-January and others, including the Defense Department, until early February, while lawmakers continue to work on fiscal full-year funding plans. Lawmakers missed their initial annual deadline of Sept. 30 to finish that work, prompting the need for an initial extension to Nov. 17 and now another one.