In the days after the Jan. 6 attack on the Capitol, the phone lines and websites of local election officials across the country were jumping: Tens of thousands of Republicans were calling or logging on to switch their party affiliations.
In California, more than 33,000 registered Republicans left the party during the three weeks after the Washington riot. In Pennsylvania, more than 12,000 voters left the G.O.P. in the past month, and more than 10,000 Republicans changed their registration in Arizona.
An analysis of January voting records by The New York Times found that nearly 140,000 Republicans had quit the party in 25 states that had readily available data (19 states do not have registration by party). Voting experts said the data indicated a stronger-than-usual flight from a political party after a presidential election, as well as the potential start of a damaging period for G.O.P. registrations as voters recoil from the Capitol violence and its fallout.
Among those who recently left the party are Juan Nunez, 56, an Army veteran in Mechanicsburg, Pa. He said he had long felt that the difference between the United States and many other countries was that campaign-season fighting ended on Election Day, when all sides would peacefully accept the result. The Jan. 6 riot changed that, he said.
“What happened in D.C. that day, it broke my heart,” said Mr. Nunez, a lifelong Republican who is preparing to register as an independent. “It shook me to the core.”
The biggest spikes in Republicans leaving the party came in the days after Jan. 6, especially in California, where there were 1,020 Republican changes on Jan. 5 — and then 3,243 on Jan. 7. In Arizona, there were 233 Republican changes in the first five days of January, and 3,317 in the next week. Most of the Republicans in these states and others switched to unaffiliated status.
Voter rolls often change after presidential elections, when registrations sometimes shift toward the winner’s party or people update their old affiliations to correspond to their current party preferences, often at a department of motor vehicles. Other states remove inactive voters, deceased voters or those who moved out of state from all parties, and lump those people together with voters who changed their own registrations. Of the 25 states surveyed by The Times, Nevada, Kansas, Utah and Oklahoma had combined such voter list maintenance with registration changes, so their overall totals would not be limited to changes that voters made themselves. Other states may have done so, as well, but did not indicate in their public data.
Among Democrats, 79,000 have left the party since early January.
But the tumult at the Capitol, and the historic unpopularity of former President Donald J. Trump, have made for an intensely fluid period in American politics. Many Republicans denounced the pro-Trump forces that rioted on Jan. 6, and 10 Republican House members voted to impeach Mr. Trump. Sizable numbers of Republicans now say they support key elements of President Biden’s stimulus package; typically, the opposing party is wary if not hostile toward the major policy priorities of a new president.
“Since this is such a highly unusual activity, it probably is indicative of a larger undercurrent that’s happening, where there are other people who are likewise thinking that they no longer feel like they’re part of the Republican Party, but they just haven’t contacted election officials to tell them that they might change their party registration,” said Michael P. McDonald, a professor of political science at the University of Florida. “So this is probably a tip of an iceberg.”
But, he cautioned, it could also be the vocal “never Trump” reality simply coming into focus as Republicans finally…