The $2 trillion stimulus package that was approved by the Senate on Wednesday contains $400 million to address one of the most uncertain impacts of the coronavirus outbreak — its potential to wreak havoc with voting, including the presidential election in November.

The figure falls far short of what state officials and voting rights experts have said is needed to ensure a safe and accurate count if the virus keeps millions of people away from polling places in primary elections and on Election Day.

The $400 million in the stimulus package is one-fifth of the $2 billion that voting experts said was needed and that some Democrats had sought. The money could only be used to help states create and staff new polling places to reduce crowding, or to increase opportunities to register online and vote by mail, according to a Senate official who declined to be named because he was not authorized to talk about specifics of the legislation.