Despite increasingly difficult math that shows him unlikely to catch Hillary Clinton in the race for the nomination, Bernie Sanders can take comfort in the fact that Democratic voters generally support his decision to keep fighting.

The latest NBC News/Survey Monkey weekly tracking poll finds 57 percent of registered Democrats and independents who lean Democratic say Sanders should stay in the race until the Democratic National Convention.

Just 16 percent say he should drop out now, according to the poll, and 25 percent he should drop out in June if he still trails Clinton in the hunt for delegates after the last primaries have taken place.

The Vermont senator has said repeatedly in recent weeks that he intends to stay in the presidential race through the Democratic National Convention in July. By doing so, he hopes building momentum through victories in late states, along with polls that show him outperforming Clinton in the general election against Republican front-runner Donald Trump, will help convince superdelegates to support him instead of Clinton.

Sanders has just 1,318 pledged delegates, compared to Clinton's 1,645. When factoring in superdelegates – the party insiders and elected officials whose votes account for about 15 percent of the delegate total – Clinton's total jumps to 2,165, just 218 short of the 2,383 delegates needed to clinch the nomination.

Sanders would need to collect 64 percent of the remaining delegates, however, to overtake Clinton's lead in pledged delegates, a task made all the more difficult by party rules that distribute the delegates proportionately. He would need overwhelming victories in all the states to come, but polls show him narrowly trailing Clinton in Indiana, which votes Tuesday, and by larger margins ahead of June primaries in California and New Jersey, the two largest prizes left on the map.

Democrats' willingness to see Sanders stay in the race, even as his path to a pledged delegate majority narrows, is in marked contrast to Republicans, who in the same survey are much less interested in seeing an extended primary.

Just 39 percent of registered Republicans and GOP-leaning independents said Texas Sen. Ted Cruz should stay in the race through the Republicans' convention in July, compared to 36 percent who said he should drop out of the race now, and 23 percent who said he should get out after California votes on June 7.

GOP voters are more eager to see Ohio Gov. John Kasich leave the race. Only about a quarter – 26 percent – say he should stay in, while 58 percent want him to drop out now and 15 percent say he should end his campaign after the voting is completed in June.

Trump has so far collected 996 delegates, including 41 delegates who are unbound but say they'll support him. He needs just 241 to clinch the nomination.

His strong showings in New York and five other states in the past several weeks makes it more likely the real estate tycoon will reach 1,237 bound delegates before the convention, ensuring his ability to win the nomination on the first ballot.