oters cast their ballot in the Indiana Primary at a fire station in Indianapolis, Tuesday, May 3. | AP Photo Poll: 6 in 10 Democratic voters want open primary process

Nearly two-thirds of Democrats and Democratic-leaning voters want the party's caucuses and primaries to be open to all registered voters rather than closed to registered party members only, according to the results of the NBC News/SurveyMonkey online tracking poll out Tuesday.

A full 63 percent on the Democratic side said the process should be open to all, while 35 percent said it should be restricted to registered Democrats. Among Republicans and Republican-leaning voters, 52 percent said the process should be open to all registered voters, while 47 percent said it should be a closed process.


Regardless, nearly six in 10 of both Democrats and Republicans surveyed said they believe the process for selecting a presidential nominee in their party to be fair. On the Democratic side, 59 percent said they found it fair, compared with 38 percent who said they did not; among Republicans and leaners, the results are the same.

Bernie Sanders' campaign has pushed for more open primaries, arguing that his supporters are being disenfranchised by the closed elections, which have largely been to Hillary Clinton's benefit. However, Sanders has benefited more from the closed caucus system, which rewards a smaller number of more committed supporters.

Clinton leads Donald Trump 48 percent to 44 percent in the latest survey matching the likely general election contenders against each other, an increase of 1 point for Clinton and a decrease of 1 point for Trump from the previous week's poll. Sanders led Trump 52 to 40 percent in his matchup with Trump, unchanged from last week.

The poll was conducted online from May 30-June 5, surveying 10,520 adults nationwide with an overall margin of error of plus or minus 1.3 percentage points, including 9,240 registered voters, with a margin of error of plus or minus 1.4 percentage points.