Dianne Feinstein, who died on Thursday at 90, was the first senator to die in office since John McCain in 2018.
But since the first Congress convened in 1789, deaths in office have been a fairly regular occurrence. “You look back in history, nearly one in 10 members of Congress have,” Jane L. Campbell, the president of the U.S. Capitol Historical Society, told me for an earlier article on the subject.
In many cases, lawmakers are replaced by a member of the same party, often in a special election or when a governor appoints a replacement, as will be the case for Ms. Feinstein, a Democrat from California. But some congressional deaths might have changed the course of legislative history. There are three notable examples from the last century alone, including one during Barack Obama’s presidency.
Death and consequences
In the 1930 midterm elections, Republicans narrowly won control of the House. But 14 representatives-elect died before Congress convened 13 months later, and voter angst over the Depression helped Democrats flip enough seats in special elections to claim a majority. They used it to pass economic relief and higher taxes on the rich — policies that were opposed by President Herbert Hoover and that would come to animate the presidency of his successor, Franklin D. Roosevelt. “They established the groundwork for the New Deal,” Andrew E. Busch, a professor of government at Claremont McKenna College, told me.
In 1954, Senate Republicans were trying to make business-friendly changes to a federal law that already restricted labor unions’ power. But the deaths of three Republican senators pushed their party below a majority, effectively switching control of the Senate to Democrats for a month. Lyndon B. Johnson, the Democratic leader at the time, saw an opportunity. He used his party’s numerical edge to send the amendments back to committee, effectively killing them.
“Lyndon Johnson was just a master tactician as a legislator and also as a president,” said Christian Grose, a political scientist at the University of Southern California who has studied the episode. “Some of what he learned I think happened during that period where he was technically the minority leader but he had more votes.”
More recently, the 2009 death of Senator Edward M. Kennedy of brain cancer — and the upset victory by Scott Brown that flipped the Massachusetts seat to Republicans — cost Senate Democrats their filibuster-proof majority. That forced the Democratic House to abandon its more progressive version of the Affordable Care Act and instead pass a stingier bill that had already cleared the Senate, which ultimately became law.
Ms. Feinstein’s death has temporarily narrowed Democrats’ Senate majority, leaving the party in control of the chamber but with less room for error. Moderates like Joe Manchin III and Kyrsten Sinema, who sometimes vote with Republicans, will have more power to sink Democratic priorities until Ms. Feinstein’s replacement is seated.
Earlier this year, Ms. Feinstein was gone from the Senate for more than two months while she recovered from shingles. She requested that a fellow Democrat temporarily take her seat on the Judiciary Committee, which was deadlocked in her absence and unable to advance some of President Biden’s nominees to serve on federal courts. But Republicans denied Ms. Feinstein’s request, and some liberals called on her to resign from the Senate.
Yet Ms. Feinstein’s temporary absence did not meaningfully slow the pace at which the Senate confirmed Mr. Biden’s judicial nominees. And after her death, top Republicans said they would not block Democrats from replacing her on the Judiciary Committee.
Ms. Feinstein’s death may not end up affecting her party’s political fortunes because Gov. Gavin Newsom of California, a fellow Democrat, will get to appoint her replacement. But seven other senators in the Democratic caucus, and five Senate Republicans, represent states led by a governor of the opposite party with the power to appoint anyone he or she chooses. That means a future vacancy could, in theory, change the Senate’s partisan makeup.
Some states have taken preventive steps. Several require the governor to appoint someone of the same party as the departing senator. In 2021, Senator Mitch McConnell — who is now 81 and has had several health scares this year — persuaded Kentucky’s Republican-controlled legislature to require the governor, currently a Democrat, to replace Mr. McConnell with a fellow Republican if his seat becomes vacant.
An aging Congress
Medical advances and longer life spans have helped drive down deaths in Congress in recent decades. Deaths among sitting senators have become rarer still. As a group, members of Congress are wealthier, better educated and have better access to high quality health care than the general population, factors that all correlate with longer life spans.
Perhaps as a result, many lawmakers are choosing to remain in office well into old age. The memberships of both the House and Senate have trended older in recent decades, with the Senate’s median age topping 65 this year, according to a FiveThirtyEight analysis. The share of lawmakers in their 70s spiked to a record 23 percent last year, according to data published by Insider. Nineteen current lawmakers — including Senator Chuck Grassley (90), Senator Bernie Sanders (82) and Representative Nancy Pelosi (83) — are even older. Until her death, Ms. Feinstein was Congress’s oldest sitting member.
In polls, many voters say they favor age limits for elected officials or express anxiety about older leaders like Mr. Biden (80) and former President Donald J. Trump (77).
The country may see more congressional deaths as lawmakers continue serving into old age, said William J. Kole, a former Associated Press journalist and the author of “The Big 100: The New World of Super-Aging.”
“The electorate is really troubled by the prospects of us becoming a full-blown gerontocracy,” he said. “If we are not already one.”