Bill Clinton's DNC speech tried to cast a big tent of potential Kamala Harris voters.Justin Sullivan/Getty ImagesThe DNC has shown Democrats really want to win over Republican and independent voters.Several Republicans have spoken at the convention, including former Trump White House officials.Speeches from Bill Clinton and Oprah on night three also seemed aimed at making a broad appeal.Here's something you don't usually expect: partisans speaking at the convention of the opposing political party.But that's exactly what's been unfolding at the Democratic National Convention in Chicago this week.It's just one indication of what Vice President Kamala Harris and the Democrats are really after between now and Election Day: the vote of both independents and disillusioned Republicans.Even before Harris was the party's nominee, the Biden-Harris campaign was making moves to win over Republicans.