I'm not sure how many (if any) actually do. Do you have a source? For example, Diane Rehm got in hot water for assuming Bernie Sanders had it based on something she saw on the internet:

"As the site Jewish Journal noted, the list Rehm may be referring to seems to be one that has circulated on the Internet for several years concerning U.S. government officials and members of Congress who allegedly hold dual citizenship with Israel.

"That's some of the nonsense that goes on in the Internet. But that is absolutely not true," Sanders said."

https://www.politico.com/blogs/media/2015/06/nprs-diane-rehm...

Politifact has debunked the particular Facebook post in question that may have originally led Diane astray:

https://www.politifact.com/factchecks/2019/feb/25/blog-posti...

That being said, backing Israel is obviously incredibly smart politics in heavily-evangelical Christian parts of the US:

"Some Christian Zionists believe that the gathering of the Jews in Israel is a prerequisite for the Second Coming of Jesus. The idea has been common in Protestant circles since the Reformation that Christians should actively support a Jewish return to the Land of Israel, along with the parallel idea that the Jews ought to be encouraged to become Christians as a means of fulfilling biblical prophecy."

https://en.wikipedia.org/wiki/Christian_Zionism

"Notably, LifeWay found that 80% of the surveyed evangelicals believe that the modern rebirth of Israel and the return of millions of Jews to that land are a fulfillment of Bible prophecy and show "we are getting closer to the return of Jesus Christ." Some evangelicals say that prophecy includes a belief in a final battle of Armageddon that concludes with Jews accepting Jesus Christ as their savior."

https://www.npr.org/2019/08/25/753720351/as-u-s-jews-cool-to...

And, as part of the ongoing discourse about this weird relationship, rep Ilhan Omar got absolutely raked over the coals for this comment, which should give you some idea of how politically important public, unconditional support for Israel can be in the US:

"First, when questioning long-standing congressional support for Israel, she blamed the campaign money provided by pro-Israel supporters. “It’s all about the Benjamins, baby,” she tweeted."

https://www.theatlantic.com/ideas/archive/2019/03/ilhan-omar...

The article (granted, it's an opinion piece) goes on to condemn her for being a horrible anti-Semitic such and such for uttering those six words. Important lesson, never even think the word AIPAC while you're tweeting if you're an American politician. Nothing good can come of it.

Although, there are voices from the inside condemning this, as in this opinion piece in Haaretz by a former AIPAC lobbyist:

'Deploying very stark language, naming the Democratic Party, picturing three Democratic congresswomen (two of whom are freshmen) and throwing around accusations of anti-Semitism and of being "more sinister" than international terrorist groups is jarring at best. And although AIPAC subsequently pulled the Facebook ad and issued an apology via Twitter, labeling their own ad "imprecise, poorly worded, inflammatory…that distorted our message" a spokesperson still explained the ad was "popular with our target audience."'

https://www.haaretz.com/us-news/.premium-aipac-s-fall-i-work...

It's a weird, weird relationship between two countries linking geopolitics, religion, history, blah, blah, blah.