Is it due to Trump's extreme rhetoric or conspiracy theories about the White House's disaster management after hurricanes Helene and Milton? Are voters worried about the prospect of getting a female commander-in-chief?
Political analysts in the US have no clear explanation for why Democrat Kamala Harris has markedly declined in popularity over the past few weeks. The Vice President is campaigning intensively in the crucial swing states and has made several sought-after media appearances.
Summer has turned to autumn, the signs of tailwind for Harris have ceased, notes opinion expert Jeff Horwitt for TV channel NBC.
Nothing different?
His colleague Bill McInturff believes that the development is due to Harris not being able to demonstrate clear differences between her and President Joe Biden's leadership. In an ABC interview last week, Harris said she "can't think of anything" she would have done differently than her boss.
I've been involved in most important decisions, she said in a clip that went viral.
Later, Harris returned to the subject and said that, unlike Biden, she plans to have a Republican in her cabinet.
Bill McInturff concludes that the election for many Americans becomes a choice between two sitting presidents – and that many think they had it better under Trump's time.
A country in decline
Add to that Donald Trump's daily attacks on Harris, mainly targeting her intelligence.
He has also spread exaggerated, in some cases false, information about violent immigrant groups in the US, and threatened to deploy the military against left-wing groups. The rhetoric is in line with Trump's description of the US as a country in decline, a development he claims only he can reverse.
The former President has now surpassed Harris in all seven identified swing states, including Wisconsin, where the Vice President led until Friday. However, in all swing states, it is very close, and the difference often lies within the margin of error. But in Arizona and North Carolina, Trump has a lead of one percentage point or more, according to Real Clear Politics' average.
The trend is also seen among betting companies. According to the site Election Betting Odds, which compiles odds from six betting companies, Trump's chances of winning on November 5 have risen to 57.5 percent. Harris' chances have fallen to 41.7 percent.
Democrat Kamala Harris currently has the support of 49.2 percent of Americans, and Republican Donald Trump has the support of 47.7 percent, according to Real Clear Politics' compilation of current measurements. However, the complex US electoral system, where voters vote for electors in each state, means that a candidate can win the election without having majority support.
The electoral system means that the election is decided in a few so-called swing states. Here's how the candidates' support looks in percent in these states.
The number of electoral votes in each swing state is in parentheses, and to win the presidential election, a candidate needs the support of at least 270 electors.
Pennsylvania (19): Trump: 47.9; Harris: 47.4
Georgia (16): Trump: 48.7; Harris: 47.8
North Carolina (16): Trump: 48.5; Harris: 47.5
Michigan (15): Trump: 48.8; Harris: 47.4
Arizona (11): Trump: 48.8; Harris: 47.4
Wisconsin (10): Trump: 47.9; Harris: 47.8
Nevada (6): Trump: 47.7; Harris: 47.2
The presidential election will be held on Tuesday, November 5.
Source: Real Clear Politics