2016 United States presidential election

Board of elections worker Valerie Tyree cleans an election booth after a person voted in the state's primary election at the Cuyahoga County Board of Elections, Tuesday, April 28, 2020, in Cleveland. The first major test of an almost completely vote-by-mail election during a pandemic is unfolding Tuesday in Ohio, offering lessons to other states about how to conduct one of the most basic acts of democracy amid a health crisis. (AP Photo/Tony Dejak)

Former US Secretary of State, Hillary Clinton, poses for the photographers during a photo-call for the film 'Hillary' ' during the 70th International Film Festival Berlin, Berlinale in Berlin, Germany, Tuesday, Feb. 25, 2020. (AP Photo/Markus Schreiber)

FILE - In this Dec. 9, 2019, file photo, former first lady Michelle Obama listens to female students at the Can Giuoc high school in Long An province, Vietnam. Seeking to unite Democrats, Joe Biden has raced to line up supporters ranging from progressive icon Bernie Sanders to former President Barack Obama, whose administration sometimes irked liberals. But the person with the most influence may be Michelle Obama. (AP Photo/Hau Dinh, File)

In this April 7, 2020, photo, voters masked against coronavirus line up at Riverside High School for Wisconsin's primary election in Milwaukee. The devastating coronavirus pandemic stands poised to reshape the political map this November. The virus has pummeled battleground states and alarmed Republicans who see early warning signs for an election that could be a referendum on President Donald Trump’s management of the crisis. (AP Photo/Morry Gash)

FILE - In this Feb. 10, 2020 file photo, Democratic presidential candidate Sen. Bernie Sanders, I-Vt., accompanied by Rep. Alexandria Ocasio-Cortez, D-N.Y., left, takes the stage at campaign stop at the Whittemore Center Arena at the University of New Hampshire in Durham, N.H. Choosing a presidential candidate based primarily on loathing the alternative is not the strongest of electoral strategies. That's why leaders of the progressive movement say many Americans who were enthralled by Bernie Sanders and his slogan of “Not Me. Us,” won’t be as likely to settle for Joe Biden. (AP Photo/Andrew Harnik)

FILE - In this Jan. 4, 2017 file photo, Vice President Joe Biden, left, watches President Barack Obama, center, at Conmy Hall, Joint Base Myer-Henderson Hall, Va. (AP Photo/Susan Walsh)

Election officials Britt Bermingham, left, and Terry ?Perry count ballots as City of Milwaukee Election Commission workers were processing absentee ballots on the fourth floor of an office building at 501 W. Michigan Ave. in Milwaukee on Monday, April 13, 2020.(Mike DeSisti/Milwaukee Journal-Sentinel via AP)

Democratic presidential candidates Sen. Bernie Sanders, I-Vt., left, and former Vice President Joe Biden, shake hands on stage Friday, Feb. 7, 2020, before the start of a Democratic presidential primary debate hosted by ABC News, Apple News, and WMUR-TV at Saint Anselm College in Manchester, N.H. (AP Photo/Charles Krupa)

This image from video provided by the Bernie Sanders presidential campaign shows Sen. Bernie Sanders, I-Vt., as he announces he is ending his presidential campaign Wednesday, April 8, 2020, in Burlington, Vt. (Bernie Sanders for President via AP)

People line up to vote at Riverside High School during the primary in Milwaukee on Tuesday, April 7, 2020. Voters lined up to cast ballots across Wisconsin on Tuesday, ignoring a stay-at-home order in the midst of the coronavirus pandemic to participate in the state's presidential primary election. (Mike De Sisti/Milwaukee Journal-Sentinel via AP)