Is the blue wave coming? U.S. midterm election voting: Democratic advantage may change due to "hidden voters"

Voting on the 3rd for the US midterm elections. With high expectations of overthrowing the Republican congressional majority, the Democratic Party has maintained a stable lead in polls for months before the election, taking advantage of current President Trump's record-low administrative satisfaction and the public's strong dissatisfaction with high inflation and soaring cost of living. All signs seem to indicate that the Democratic Party will usher in a big victory.

The British Broadcasting Corporation (BBC) reported that according to the final pre-election polls, the Democratic candidate's leading number of seats in the House of Representatives constituencies has far exceeded the 218-seat threshold required to seize control. In the fierce battle in the Senate that affects high-level personnel and judicial appointments, the Democratic Party is also locked in a tug of war with its opponents, and even leads slightly. A recent New York Times poll showed that the Senate race in South Carolina was a rare tie, and Trump won the state by as much as 18 percentage points in the 2024 election; a CNN survey also pointed out that the Democratic Party is temporarily leading in Texas, Kansas and Maine.

However, this seemingly unstoppable "blue wave" has caused experts to worry about the accuracy of the polls. In recent American political history, there have been many cases of inaccurate polling. Trump's vote share for winning the White House in 2016 and 2024 far exceeded pre-election predictions. In the Michigan Democratic Senate primary earlier this year, polls predicted that progressive candidate Abdul El-Sayed would win by double digits, but the final margin was only 1%.

Clifford Young, president of the public affairs department of Ipsos, pointed out that the difficulty of polling has increased significantly in recent years. In addition to people abandoning indoor phones, "conservatives, especially far-right conservatives, are more anti-establishment in nature. They do not participate in anything and hate the system." If Republican voters are systematically underestimated and polling models fail to detect this "hidden voter" phenomenon, the data will easily tilt toward the Democratic Party.

Although the general environment is favorable to the Democratic Party, historical experience shows that it is still extremely difficult to replicate the "red tide" in which the Republican Party swept more than 60 seats in the House of Representatives in 2010.

First of all, most of the constituencies that are fiercely contested this time are the "home field" that Trump easily won two years ago. Secondly, after years of gerrymandering, the number of free seats that actually change hands between the two parties has been significantly reduced. More importantly, as the political polarization in the United States deepens, the number of swing voters has dropped sharply, and experts have described the voter structure as "rigid". In addition, the Republican Party has a huge financial advantage at the end of the election campaign, which is enough to launch aggressive negative ads, which adds uncertainty to the election.

However, even taking into account the "hidden right" error of past presidential elections, current polling averages still show that the Democratic Party is very likely to do well. One of the obvious indicators is that in the final days of the election, Trump was forced to return to campaigning in states that he had easily won in 2024, making Democrats more convinced that the situation for conservative candidates is far more difficult than it appears on the table.

But the biggest variable in the election campaign is always the people. Young emphasized: "We (polling agencies) are trying to do better, but the problem we face is that we are dealing with 'people'. People are not so easy to predict." In many closely contested states, undecided voters who express their opinions at the last minute will become a key force in determining who can dominate the Capitol.