USD fell against its major rivals in the European session on Monday as investors' focus shifted to U.S. politics.  The U.S. Dollar Index (DXY), measuring the U.S. currency's value relative to a basket of foreign currencies, dropped 0.50% to 94.17.

The first presidential debate between U.S. President Donald Trump and Democratic candidate Joe Biden is scheduled to take place on Tuesday, September 29. Ahead of the first debate, Biden leads Trump by seven points nationally, based on an average of recent polls, according to RealClearPolitics. 

Market participants also digested the New York Times' report that President Trump paid just $750 in U.S. income taxes in both 2016 and 2017. 

Also weighing on investors' sentiment was a lack of confidence that the U.S. lawmakers would be able to approve another stimulus package before the presidential election on November 3 as well as growing worries that the economic recovery was slowing as many stimulus programs had expired. House Speaker Nancy Pelosi said Sunday that a stimulus deal is still possible.