Over the course of this election cycle so far, 25 major presidential candidates — by FiveThirtyEight’s definition — have entered the race for the Democratic nomination. That gobsmacking number sparked criticism that there were perverse incentives to run for president even if a candidate plainly had no shot at winning — namely, that the exposure from a national run would help them sell books or land them a cable-news gig. But as 2019 has worn on, it’s become clear that running for president to raise one’s national profile isn’t without its risks. Some candidates have suffered adverse effects from their presidential runs: It’s hurt their political standing back home.

I dug up as many polls as I could find of the 2020 presidential candidates’ popularity — not nationally or among Democratic primary voters, but among all respondents in their home jurisdiction (the state, district or city that they represent ). Then I looked for polls conducted shortly before they announced their presidential campaign and compared the before and after pictures. What I found was that almost everyone has seen their net popularity decline, although some candidates have suffered more damage than others.

Take, for example, Sen. Kamala Harris. In a September 2018 poll by the Public Policy Institute of California, 44 percent of adults approved of Harris’s job performance, while only 27 percent disapproved — a net approval rating of +17 points. One year later, however (and after Harris had been on the national campaign trail for nine months), 40 percent of adults approved of her job performance, while 37 percent disapproved — a net approval rating of only +3 points. At least two other pollsters, Morning Consult and Quinnipiac University, also show that Harris’s net approval rating at home has dropped over the past several months.

Meanwhile, Sen. Elizabeth Warren may be winning the hearts of Democratic primary voters nationwide, but she is losing support among her own constituents in Massachusetts. In May 2018, a WBUR/MassINC poll found that Massachusetts voters had a favorable impression of Warren, 53 percent to 33 percent. But by October of this year, her favorable rating was 48 percent and her unfavorable rating was 35 percent. Morning Consult’s recurring poll also found the same 7-point drop in her net job approval rating since she started running for president.

It’s the same story with former 2020 candidate Sen. Kirsten Gillibrand. According to the Siena Research Institute, her net favorability rating (favorable rating minus unfavorable rating) in New York has declined from +17 in January to +5 in September. And Morning Consult has observed a 7-point drop in her net approval rating since late 2018.

In fact, this may help explain why Gillibrand dropped out so early. Hyped as a presidential candidate for years and possessing a sizable financial war chest, Gillibrand was not running a vanity campaign — she appeared in it to win it. But when it became clear that her campaign was not getting any traction, it probably made sense for her to drop out early and rebuild her relationships at home; at age 52, she still has a long political future.

Sen. Cory Booker may be approaching this point as well. According to Monmouth University polling, in April 2018, 54 percent of New Jersey voters approved of his job performance and 31 percent disapproved; in September 2019, though, only 45 percent approved and 40 percent disapproved. Unlike California, Massachusetts and New York, New Jersey is not so blue that any Democratic nominee can be considered a sure bet to win a Senate race, so Booker’s presidential run could prove to be a real liability to his reelection campaign if his approval continues to fall. (Unlike Harris, Warren and Gillibrand, Booker is also up for reelection in 2020.) That said, Morning Consult, the only other pollster I found that asked about Booker in New Jersey this year, finds that his net approval has declined less precipitously — from +14 in the last three months of 2018 to +10 in July-September 2019.

Indeed, according to Morning Consult, which conducts quarterly polls of every senator’s and governor’s approval ratings, not every 2020 candidate has stirred discontent back home. Washington Gov. Jay Inslee, who dropped out in August, did not overstay his welcome in the race, and his image has largely remained intact; he sports the same +12 net job approval rating now as he did in late 2018. Morning Consult also pegs Sen. Bernie Sanders as the most popular senator in the country among each senator’s own constituents, in terms of raw approval rating. It would seem that his presidential ambitions haven’t bothered Vermonters, as his +35 net approval rating is only 1 point worse than it was before he launched his campaign.

On the other hand, former Colorado Gov. John Hickenlooper, Sen. Michael Bennet and Montana Gov. Steve Bullock may have tarnished their images somewhat, though not too much, by running for president; per Morning Consult, their net approval ratings each fell by 4 points. And while Sen. Amy Klobuchar’s net approval rating took an 8-point hit in Minnesota, she remains extremely popular overall; she went from a 58 percent approval and 27 percent disapproval to 55 approval, 32 disapproval (still very impressive in a purple state like Minnesota).

Finally, no one ended their presidential campaign in a worse position at home than New York City Mayor Bill de Blasio. According to the Siena Research Institute, in April 2019, a few weeks before launching his presidential campaign, 44 percent of voters in New York City had a favorable opinion of de Blasio, while 50 percent had an unfavorable opinion. But that somehow got even worse after he jumped into the race. In Siena’s September poll, de Blasio’s favorable rating in New York City was down to 33 percent, and his unfavorable rating was up to 58 percent. It’s little wonder that he pulled the plug on his campaign shortly thereafter.

One of the 25 (now 16) major candidates in the Democratic primary will (most likely) earn a place in history as the party’s nominee — and perhaps the 46th president of the United States. But the others will go limping home, and many will resume their prior political careers. As this data shows, most of them will be now worse off with their home constituencies. Running for president may carry the possibility of national fame (not to mention national office), but we ought to remember that there are real pitfalls to it as well — and one of the big ones is squandering your existing political career if you fail.

CORRECTION (Nov. 11, 2019, 12:50 p.m.): A previous version of this article incorrectly described a May 2019 survey as WBUR’s most recent poll testing Warren’s favorable and unfavorable ratings in Massachusetts. WBUR conducted a more recent survey in October. The text and chart have been updated to reflect the results of the October poll.