WASHINGTON — The House Intelligence Committee is racing to complete its investigation of Russia’s interference in the 2016 presidential election, scheduling a host of witness interviews here and in New York for next week as Congress heads for its break, and, Democrats said, leaving other leads unfollowed.

Some of the most important witnesses are to be interviewed in New York by committee staff early next week, possibly leaving Democrats to choose between attending those depositions or voting on the massive tax bill coming before the House.

And in an indication that Republicans hope to wrap up their probe, the House committee has yet to schedule a single interview after the holidays, according to two committee officials familiar with the schedule. That has left Democrats fearful that the majority is trying to finish the investigative portion of its work by the end of next week, before the committee can connect the dots on one of the most serious efforts by a hostile foreign actor to hijack American democracy.

“I feel no need to apologize for concluding an investigation,” said Representative Trey Gowdy of South Carolina, one of the Republicans leading the investigation.