华盛顿-独立总统候选人小罗伯特·F·肯尼迪在三次全国民意调查中已经达到15%或更多。再多一个，他就会遇到一个CNN的基准有资格参加6月27日辩论民主的乔·拜登总统和共和党假定提名人唐纳德·特朗普.

　　但随着11月大选的临近，肯尼迪不能指望保持目前的支持率。

　　美联社(Associated Press)对1980年以来盖洛普(Gallup)数据的分析显示，第三方候选人在选举前几个月看似拥有民意调查势头，但在投票箱中却远远落后，这种情况非常普遍。

　　这并不意味着现在关于肯尼迪的民意调查是错误的。他们只是不能预测大选将会发生什么。

　　研究表明，人们不擅长预测自己未来的行为，投票还有几个月。今年有两位非常不受欢迎的候选人2020年的复赛选民也可能利用他们早期对第三方候选人的支持来表达他们对主要政党选择的失望。最终，选民可能会支持他们认为他们的投票会产生影响的候选人，也可能决定不投票。

　　第三方的概念已经流行很久了。

　　1999年盖洛普进行的一项民意调查发现，三分之二的美国成年人表示，他们支持第三个政党，让总统、国会和州政府官员的候选人与共和党人和民主党人竞争。(美联社的分析使用了盖洛普的数据，因为盖洛普在美国有着高质量民意调查的悠久历史。)

　　大约60%的美国成年人说盖洛普民意测验自2013年以来，共和党和民主党在代表美国人民方面做得如此糟糕，以至于需要第三个主要政党。在最新的盖洛普民意测验中，这种热情大部分被无党派人士所携带:75%的人认为需要第三个政党。大约60%的共和党人和略低于一半的民主党人(46%)认为有必要制定替代方案。

　　印第安纳大学政治科学系名誉教授马乔里·赫尔希(Marjorie Hershey)说，美国人通常喜欢第三个政党的想法，直到具体细节出现，如该党的政策和提名人。

　　“这是一个象征性的概念。我想要更多的选择吗?好吧，当然。好时表示:“每个人都希望有更多的选择，更多的冰淇淋选择和更多的快餐选择。”“但如果你开始谈正题，谈论玉米卷还是汉堡，那就是完全不同的选择了，对吗?”

　　这种对第三方候选人的假想支持通常会很快瓦解。

　　美联社的分析调查了自1980年大选以来在全国范围内获得至少3%选票的每一位独立和小党派总统候选人的投票情况。

　　在包括1980年、1992年和2016年总统竞选在内的多次选举中，第三方候选人的早期投票率远高于其最终投票份额。例如，在1980年5月和6月进行的民意调查中，21%至24%的登记选民表示他们希望看到独立候选人约翰·安德松来自伊利诺伊州的资深共和党众议员，在与共和党人罗纳德·里根和民主党现任议员吉米·卡特竞选总统时获胜。安德森赢得了7%的选票。

　　部分问题是早期的民意调查往往与实际的大选投票大相径庭。

　　盖洛普高级编辑杰弗里·琼斯说，选民“不知道从现在到选举期间会发生什么”。“竞选中会出现可能改变他们思维方式的事情。“

　　安德森去世几十年后，2016年总统竞选期间进行的民调显示自由党候选人获得了支持加里·约翰逊在5月至7月进行的登记选民民意调查中，前新墨西哥州州长。这导致一些人预测他可能在几十年内比任何第三方候选人都做得好。约翰逊在那次选举中赢得了大约3%的选票。

　　约翰逊告诉美联社，他认为他的名字应该被包括在更多的民意调查中，尽管他在用于确定辩论资格的调查中。

　　他还认为独立候选人在筹款方面难以与主要政党候选人相提并论。

　　“首先最重要的是钱。约翰逊说:“如果人们认为你没有获胜的可能，他们就不会捐款。“我并没有把自己排除在这个等式之外。听着，我会把钱给一个我知道会输的人吗?我宁愿去考艾岛度假，”约翰逊在与家人开车去夏威夷旅行时接受采访时说。

　　美国的选举制度使得第三方很难茁壮成长。尽管如此，即使没有获胜，也有可能产生重大影响。

　　亿万富翁商人罗斯·佩罗是当代最成功的例子之一。他在1992年竞选总统时赢得了19%的选票。但这大大低于他在早些时候的投票中的支持率。在当年5月至7月进行的民意调查中，30%至39%的登记选民表示他们将投票给佩罗。

　　已经有理由相信，至少肯尼迪的部分民调支持可能是海市蜃楼。(肯尼迪竞选团队没有回应置评请求。)

　　ACNN去年夏天进行的民意调查他在竞选民主党提名时发现，10个考虑支持他的民主党人中有2个表示他们的支持与肯尼迪的名字或他的家庭关系有关。另有17%的人表示他们对他了解不够，希望了解更多，而只有12%的人表示是因为支持他的观点和政策。

　　弗吉尼亚大学米勒中心的总统研究专家芭芭拉·佩里说:“肯尼迪的名字是一个与众不同的变量。”。“他身上有很多情感，我可以说是安德森、佩罗、(拉尔夫)纳德和约翰逊案件中所没有的。”

　　也有一些证据美国人利用对肯尼迪的支持来表达对拜登和特朗普的失望。

　　赫尔希指出，对许多人来说，总统选举在发生前几周可能会感到抽象，所以对早期的民调数字持保留态度是有好处的。

　　赫尔希说，这样的民意调查“不一定反映实际的政治问题”。"它们反映了人们对生活的普遍看法。"

　　Why Robert F. Kennedy Jr.'s current presidential polling numbers might not hold up

　　WASHINGTON --Independent presidential candidateRobert F. Kennedy Jr.has reached 15% or more in three approved national polls. One more, and he will have met one ofCNN's benchmarksto qualify for thedebate June 27with DemocraticPresident Joe Bidenandpresumptive Republican nominee Donald Trump.

　　But Kennedy cannot count on maintaining his current level of support as the November election nears.

　　It is pretty common for third-party candidates to look like they have polling momentum in the months before an election, only to come up far short at the ballot box, according to an Associated Press analysis of Gallup data going back to 1980.

　　That is not a sign that the polls about Kennedy are wrong right now. They just are not predictors of what will happen in the general election.

　　Studies have shown that people are bad at predicting their future behavior, and voting is months away. And in a year with two highly unpopular candidates ina rematch from 2020, voters may also use their early support for a third-party candidate to express their frustration with the major party choices. In the end, voters may support the candidate for whom they feel their vote can make a difference or they may decide not to vote at all.

　　The concept of a third party has been popular for a long time.

　　A poll conducted by Gallup in 1999 found two-thirds of U.S. adults said they favored a third political party that would run candidates for president, Congress and state offices against Republicans and Democrats. (The AP analysis used Gallup data, when available, because Gallup has a long history of high-quality polling in the United States.)

　　About 6 in 10 U.S. adults have said inGallup pollingsince 2013 that the Republican and Democratic parties do “such a poor job representing the American people” that a third major party is needed. In the latest Gallup polling, much of that enthusiasm is carried by independents: 75% say a third party is needed. About 6 in 10 Republicans and slightly fewer than half of Democrats (46%) say an alternative is necessary.

　　Marjorie Hershey, a professor emeritus in the political science department at Indiana University, said Americans generally like the idea of a third party until specifics emerge, such as that party's policies and nominees.

　　“It’s a symbolic notion. Do I want more choices? Well, sure. Everybody always wants more choices, more ice cream choices, more fast-food choices,” Hershey said. “But if you start to get down to brass tacks and you talk about, so would it be tacos or burgers, then that’s an entirely different choice, right?”

　　That hypothetical support for third-party candidates often breaks down quickly.

　　The AP analysis looked at polling for every independent and minor party presidential candidate who received at least 3% of the popular vote nationally going back to the 1980 election.

　　In multiple elections, including the 1980, 1992, and 2016 presidential races, third-party candidates hit early polling numbers that were much higher than their ultimate vote share. For instance, in polls conducted in May and June 1980, between 21% and 24% of registered voters said they would like to see independent candidateJohn Anderson, a veteran Republican congressman from Illinois, win when he ran for president against Republican Ronald Reagan and Democratic incumbent Jimmy Carter. Anderson went on to earn 7% of the popular vote.

　　Part of the problem is that early polls often look quite different from the actual general election vote.

　　Voters "don’t know what’s going to happen between now and the election,” said Jeffrey Jones, a senior editor at Gallup. “Things are going to come up in the campaign that could change the way they think.”

　　Decades after Anderson, polls conducted during the 2016 presidential campaign put support for Libertarian Party candidateGary Johnson, a former New Mexico governor, at between 5% and 12% in polls of registered voters conducted from May to July. That led some people to predict that he could do better than any third-party candidate in decades. Johnson won about 3% of the vote in that election.

　　Johnson told the AP that he believes his name should have been included in more polls, though he was in surveys used to determine eligibility for debates.

　　He also contends that independent candidates struggle to match major party candidates in fundraising.

　　“It’s money, first and foremost. People don’t donate if they don’t think that you have a possibility of winning," Johnson said. "I’m not excluding myself from that same equation. Look, am I going to give money to somebody that I know is going to lose? I’d rather go on a vacation in Kauai,” Johnson said in an interview while driving with his family on a trip in Hawaii.

　　The American electoral system makes it hard for third parties to thrive. Still, it is possible to have a significant impact without coming close to winning.

　　Billionaire businessmanRoss Perotis among the most successful modern-day examples. He won 19% of the vote when he ran for president in 1992. But that was substantially lower than his support in earlier polling. In polls conducted from May to July of that year, between 30% and 39% of registered voters said they would vote for Perot.

　　There are already reasons to believe that at least some of Kennedy’s polling support may be a mirage. (The Kennedy campaign did not respond to a request for comment.)

　　ACNN poll conducted last summerwhen he was running for the Democratic nomination found that 2 in 10 Democrats who would consider supporting him said that their support was related to the Kennedy name or his family connections. An additional 17% said they did not know enough about him and wanted to learn more, while only 12% said it was because of support for his views and policies.

　　“A variable that is so different from all these other people is the Kennedy name,” said Barbara Perry, an expert in presidential studies at the University of Virginia's Miller Center. “There’s a lot of emotion around him that I would say was not there in the Anderson, Perot, (Ralph) Nader and Johnson cases.”

　　There also issome evidencethat Americans are using support for Kennedy to express frustration with Biden and Trump.

　　Hershey notes that for many people, presidential elections can feel abstract until a few weeks before it happens, so it is good to take early poll numbers with a grain of salt.

　　Such polls “don’t necessarily reflect actual political issues,” Hershey said. “They reflect general views about life.”