WASHINGTON — They are a disparate foursome: the chamber’s leading Republican centrist, a minister who embraces public service as a calling, a seasoned dealmaker and a high-profile presidential contender.

These four Republican senators — Susan Collins of Maine, James Lankford of Oklahoma, Roy Blunt of Missouri and Marco Rubio of Florida — are emerging as a bloc integral to the Senate Intelligence Committee’s investigation into Russian meddling in the 2016 presidential election.

The investigation is widely considered the premier inquiry, the one with the necessary jurisdiction and the best chance of producing a credible outcome. These four senators loom large as a crucial element in getting there.