Several recent polls have shown that Harris's poll support has increased significantly in recent months, both nationwide and in key swing states, and has surpassed Trump, indicating that her chances of winning this election are gradually increasing.

A poll released by NBC on Sunday showed Harris leading Trump by 5 percentage points. The survey found that respondents' opinions of her have significantly improved since she became the Democratic presidential candidate. NBC conducted the poll of 1,000 registered voters from September 13 to 17, with a margin of error of 3 percentage points.

The poll showed that when asked about their views on Harris as the nominee, 48% said they were positive, compared with 32% in July. The last time an American politician's approval rating increased so much was President Bush after the September 11, 2001 terrorist attacks.

When asked about Trump, 40% of respondents said they had a positive view of him, compared with 38% in July.

CBS conducted a survey of 3,129 registered voters from September 18 to 20. The survey showed that Harris's support rate has increased compared with August: in August this year, CBS polls showed that Trump and Harris's support rates were 50% to 50%, respectively. Now, Harris's support rate among American voters is 4 percentage points ahead of Trump, 52% to 48%, respectively.

The latest Guardian survey also showed the same result. According to the Guardian's 10-day average of polls ending on September 19, Harris's lead over Trump in the polls has expanded to 2.6 percentage points, with the polling approval ratings of the two parties at 48.5% to 45.9%. A poll conducted by Morning Consult of more than 11,000 respondents showed that Harris led Trump by 51% to 45%, the largest polling approval rating advantage she has achieved since replacing Joe Biden as the Democratic presidential candidate. The fivethirtyeight polling data platform, which comprehensively compiles data from multiple polls, shows that Harris now leads Trump nationwide with a 48.4% approval rating, while the latter has a 45.5% approval rating.

While national polls provide important signals about voters' views, in the final election, the winner is determined by the results of the Electoral College in each state, which means that the voting results in a few battleground states may be the key to determining the balance of victory.

But polls show Harris also appears to be ahead in key battleground states: A New York Times/Siena poll shows Harris leading Trump 50%-46% in Pennsylvania, which many commentators believe is the most important swing state in determining the outcome of this election.

A Quinnipiac University poll showed similar results: Harris leads Trump 51% to 45% in Pennsylvania. In addition, the Quinnipiac University poll also showed that Harris also leads Trump in two neighboring battleground states, Michigan and Wisconsin, with a lead of 5 percentage points and 1 percentage point respectively.

Amy Walter, publisher and editor-in-chief of the nonpartisan election forecasting organization Cook Political Report, said in an interview: "She (Harris) has been able to turn this race from a referendum on Joe Biden to a referendum on Donald Trump."

Economist and author of the Morning Consult research report, Sofia Baig, analyzed that although Harris was the vice president, she successfully avoided the public's accusations against Biden's policies, and at the same time, some of her campaign promises won the support of voters. "Although many voters are dissatisfied with the current economy, they believe that Vice President Harris has less responsibility than President Biden," she wrote. "Throughout the election cycle, voters have consistently said that they believe former President Trump can handle economic issues better than Biden, but Harris has narrowed the gap."