U.S. President Joe Biden's public approval rating fell for a fourth straight week to 36% matching its lowest level last seen in late May, according to a Reuters/Ipsos opinion poll completed on Wednesday.

The president's approval rating has stayed below 50% since August, a warning sign that his Democratic Party could lose control of at least one chamber of the U.S. Congress in the Nov. 8 midterm elections.

Thirty-four percent of Americans say the economy is the most important issue currently facing the United States. Biden has been plagued by 40-year-highs in inflation, with Russia's invasion of Ukraine restricting global fuel supply and supply chains still constrained by the COVID-19 pandemic.

Among his own party, Biden's approval rating remains largely unchanged since last week - at 73% compared to 74% on June 15. In August, 85% of Democrats approved of Biden's performance.

But among Republicans, Biden's rating slipped to 7% compared to 11% on June 15. Only 18% of Americans think the country is headed in the right direction.

Biden's approval rating is approaching - but has not yet reached - the lowest levels seen by his predecessor, Donald Trump, who had a 33% approval rating in December 2017.

The Reuters/Ipsos poll is conducted online in English throughout the United States. The most recent poll gathered responses from 1,002 adults, including 435 Democrats and 379 Republicans. It has a credibility interval - a measure of precision - of four percentage points.