US President Joe Biden is trailing Republican presidential nominee Donald Trump in all seven major swing states, according to a poll released Tuesday.

The YouGov polling for the Times/SAY24 found Biden behind in Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin in the period stretching from July 4 - 12. That is the week after the presidential debate and before last weekend's attempted assassination of Trump.

SAY24 is a joint project from Stanford, Arizona State and Yale universities.

Biden has lost ground in every polled swing state since the survey was last conducted in March, except Arizona where he has continued to lag behind Trump by 7% among registered voters. The president had led in three of the states but has seen his support steadily erode in the past four months.

The closest races are in Michigan and Pennsylvania where Biden is behind by 1 and 3 points, respectively. Trump holds the largest leads in Arizona, Wisconsin and Nevada -- a 5% lead in the latter two.

Voters are continuing to voice dour appraisals of the economy, with at least two-thirds of respondents describing it as fair or poor, and more people are describing conditions as worsening, compared to those who think it is improving.

In another potential sign that Biden is becoming an electoral drag on his party, the YouGov poll found that Democratic Senate candidates in every swing state are well ahead of their Republican challengers, some by as much as 12 points.