9月2日是美国一年一度的劳动节，也是2024年美国大选被认为进入最后冲刺阶段的关键节点。事实上，持续伴随着不确定性的此次大选已在6月27日首次电视辩论之后的两个半月里经历了巨变。随着在任总统拜登退选、副总统哈里斯接班的快速变化，原本“两个总统”二次对决的基本结构被彻底打破，选举政治被快速抛入了难以预料的未知水域。

可以肯定的是，初选制度和实践在本次选举中彻底失效。这也预示着，下一个总统大选周期中两党特别是失败一方将更有可能率先对党内提名制度进行新一轮深入改革。毫无疑问，7月底以来的至少一个多月，哈里斯及其民主党抓住了“主场优势”，有效地改变着选情态势。7月21日拜登退选、22日哈里斯参选、经过16天选出令外界大呼意外的副手人选、随后七个摇摆州的巡回造势、直到19日到22日云集党内群星的芝加哥代表大会……所有这些都在总体上是正面积极态势，持续占据着媒体舆论的聚焦点，共同强化了民主党的势头。

8月5日开始，哈里斯在综合民调中反超特朗普，结束了去年9月以来民主党被特朗普持续压制的负面状态，直到9月初哈里斯在综合体民调中的优势仍可维持在1.5%到2%之间，并未冲破民调统计误差。与此同时，相对于拜登必须拿下宾夕法尼亚、密歇根、威斯康星中西部三州的几乎唯一路线图，哈里斯不但继续在中西部的竞争，而且也真正将南方四州不同程度上“摇摆”起来，极大丰富了民主党胜选的路线图选项。

必须看到，相比于越来越令民主党选民提不起兴趣的拜登，哈里斯的确在年轻选民、少数族裔选民以及女性选民群众中实现了更为有效的选民动员。虽然哈里斯很难在重大政策议题上摆脱拜登政府面对的“在任者劣势”，她难以让选民相信过去三年多没有做到的事情会在未来四年做到，但很显然她目前找到了一些非常有效的口号或竞选信息。

虽然具有极强的身份政治标签，但哈里斯个人却几乎不强调这些，避免重复事实上对选民无感的2016年大选时希拉里的“打破玻璃天花板”的无效呼吁，哈里斯转而选择高调宣扬的是“不要回到过去”“不要特朗普回来”。就好像哈里斯在接受CNN采访时的表现，关于自身劣势的所有问题，要么就归罪于特朗普和共和党对拜登政府政策议程的阻碍，要么就强调虽然自身也未必如何好、但现在的关键是不要让特朗普回来、不要让过去再回来。如此具有一些恐吓色彩的信息，应该说是对选民有动员效果的，特别有助于催促民主党选民的加速归队。

反而，对特朗普而言，虽然哈里斯远非无懈可击、甚至事实上有很多问题点，但如何找到一两个对这个新对手能够具有有效攻击效果的可操作信息、还要避免所谓反动员，似乎变成了一件颇为棘手的任务。

一个几乎难以想象能够经过正常初选程序而获得提名的民主党总统候选人，竟然足以改变选举态势，一举压制了来势汹汹的前总统。如此戏剧性变化，只能说明一个事实，就是今年两党的两个人选都很弱，各自存在着明显的问题与不足。进而，基本盘必然成为两党争夺的关键，而任何一方的最终胜出都是由于选民对另一方更多的厌弃。

客观而言，哈里斯在过去将近一个月的微弱稳定优势，将在9月之后的冲刺阶段面对真正考验。哈里斯在9月10日电视辩论上的表现、特朗普9月18日被定罪的量刑、特朗普遇刺未遂的调查走向、内外突发事件的牵动……这些因素中的任何一个都可能再次甚至反复改变目前选举的态势。事实上，即便是邻近选举，哈里斯就算是保持目前看到在综合民调和各关键摇摆州的微弱优势，也仍然无法确胜。换言之，在最后60多天当中，哈里斯要赢就必须扩大优势，如果维持当前优势，就是胜负难料；而对特朗普而言，就是要扭转最近颓势，增加胜算。或者我们可以说，世界在听到特朗普走回来的脚步声中又听到了哈里斯特有的笑声。

相比于2020年，2024年的民主党其实是如出一辙。2020年，他们快速集结在拜登身边、推选拜登迎战特朗普，并不是对拜登本人多么青睐，而是因为拜登是当时能够战胜特朗普的最佳人选；2024年，他们快速放弃拜登、转而支持哈里斯，也是因为哈里斯是今年民主党别无选择当中有可能战胜特朗普的最佳人选。两者的区别在于，前者恰好具有一定内外经验，足以坐稳白宫；后者却不具备足够内外政策经验。虽然民主党如今已到了只关心胜选、不关心执政的地步，但相比于当年的拜登，如今的哈里斯的确是外界难以做出更多预判的新手。

回到美国政治乃至国家发展方向维度上看，特朗普的回归可能意味着这个国家的变道转轨，特朗普则颇有历史扳道工的意味。相比而言，哈里斯的延续或许对这个国家的道路而言意义有限且间接，但很可能意味着民主党的进一步转变。未来，身份政治对哈里斯的民主党不仅仅是“政治”，而变成彻底的“身份”。也就是说，哈里斯之后的民主党必须在政治精英的“个体身份”而非“政治立场”上多元或者非白人化，民主党或将演变为一个彻底的“非白人党”，如此奇特的演变态势也将从本质上持续重塑着美国两党政治的未来。

The race for president of the United States entered its final lap recently as the country celebrated Labor Day on Sept. 2. The campaign has undergone dramatic changes, accompanied by great uncertainty, ever since the first candidate debate on June 27 between incumbent President Joe Biden and Donald Trump. When Biden suddenly withdrew and was replaced by Vice President Kamala Harris at the top of the Democratic Party ticket, election politics plunged into uncharted waters.

Democrats quickly coalesced around Harris, and the dynamics of the race changed dramatically. Following Biden's exit and his strong endorsement, Harris took over as the favorite. Sixteen days later, she announced her vice presidential running mate, which came as a big surprise, and they embarked on a tour of seven swing states. With overwhelming support from delegates, they accepted the nomination at the star-studded Democratic National Convention in Chicago. All these movements made historic headlines and built momentum.

Harris began overtaking Trump in many voter polls in early August. Meanwhile, unlike Biden, who saw winning Pennsylvania, Michigan and Wisconsin as the only path to victory, Harris successfully achieved competitiveness in at least four Southern states while continuing to compete for the Rust Belt states of the upper Midwest, opening up new paths for a possible Democratic victory.

It must be noted that compared with Biden — who many Democrats feared would lose the election after his disastrous debate with Trump — Harris has effectively mobilized voters, especially young people, minorities and women. She has found some effective campaign messages of her own. She has talked about “not going back” as she has assailed Trump as a convicted felon and failed businessman who has undermined American democracy. Such messages could be effective in mobilizing voters. At the same time, Trump has found Harris hard to attack without inducing a counter-mobilization.

A Democratic presidential candidate who became the nominee outside the normal primary process has changed the race and dealt a blow to the aggressive former president. The drama does illustrate one thing, however: Both candidates are weak, each having problems and shortcomings to overcome. Their key challenge will be to reach the relatively small pool of undecided voters who can swing the vote in a few decisive districts in a handful of states.

Objectively, Harris will from now on face the real test in the sprint to Election Day, after maintaining a slim but steady lead in key states for a month. The recent debate with Trump could be an important factor.

Since Trump's sentencing in his New York hush money and election interference case was moved until after the election, other contingencies at home and abroad — which could happen at any time — may come into play before November Any one of these factors could potentially change the status quo.

Actually, Harris cannot guarantee a victory even if she can retain her slight edge over Trump in various polls in key states ahead of the election day. She must widen her lead over Trump in swing states to win. If she only maintains her current status, the election will be a toss-up. For Trump, efforts must be made to reverse his decline to increase his odds of winning. We can also interpret the situation in this way: When the world is listening to Trump trotting back and forth, Harris's signature laughter breaks in.

During this presidential election race, the Democrats are as they were in 2020. Back then, they swiftly congregated around Biden and pushed him to the nomination not because they favored him but because he was the best candidate available who could defeat Trump. This year, they abandoned Biden and turned toward Harris, also because she is the best — and arguably the only — option likely able to beat Trump.Although the Democratic Party has come now to a point at which the main concern is simply winning, not governing, Harris provides a new hand, and the outcome is difficult to predict.

In the world of U.S. politics, the return of Trump could mean the country would change tracks. By contrast, a Harris victory may have a more limited impact on the country's path forward, but it would probably precipitate further changes in the Democratic Party. In the future, identity politics will not just mean “politics” for the Democrats but brim with identity. In this way, the Democratic elite in the post-Harris era will have to be diverse, or non-white — with individual identity dominating policy. The Democratic Party will probably develop into an entirely non-white party. Such a peculiar evolution will continue reshaping the future of the U.S. bipartisan politics.