BURLINGTON, Vt. — When it comes time to make critical decisions regarding his presidential campaign, Senator Bernie Sanders often relies on a committee of two: himself and his wife, Jane Sanders.

It was Ms. Sanders who provided a medical update after her husband was hospitalized in Las Vegas last week and had two stents inserted into an artery — issuing a statement and speaking to reporters outside the hospital. When doctors confirmed to her on Thursday that Mr. Sanders had suffered a heart attack, she said, it was her decision to wait until he was discharged the next day to release that information .

And when it was time to say publicly that Mr. Sanders would be easing the pace of his campaigning after his heart attack, Ms. Sanders — who has effectively been running the campaign’s external communications in Vermont this week — stood beside him to explain the reason: His closest advisers, “especially me,” had told him to slow down.

Ms. Sanders has played a central role in her husband’s political life for decades, acting as his confidante and his closest adviser. Yet as Mr. Sanders weighs the future of his candidacy, never has it been clearer that the two of them are primarily making the calls for his campaign.