Almost half of Republicans asked in a new poll say they would like to see President Trump face a primary challenge in 2020.

A Monmouth University survey found that 43 percent of Republicans asked want to see a contested primary, although it's not clear if anyone will rise to the challenge, or who might be able to defeat him. The study said Trump would trounce Sen. Ted Cruz, R-Texas, and former Ohio Gov. John Kasich by 45 and 59 percentage points respectively. Cruz and Kasich both ran unsuccessfully against Trump in 2016 for the GOP presidential nomination.

The same poll said 49 percent of Republicans hope Trump will have a clear run to re-election next year. Those poll results were based on a subsurvey of 335 registered Republicans, and have a margin of error of 5.4 percentage points.

Among Democratic voters, former Vice President Joe Biden holds a double-digit advantage over his closest rival to become his party's standard-bearer, Sen. Bernie Sanders, the independent from Vermont who failed to become the Democrats' White House pick in 2016. Biden and Sanders earned 29 percent and 16 percent support, respectively, in a hypothetical primary. Sen. Kamala Harris of California placed third with about 10 percent of the vote.

Results among Democrats were based on a survey of 313 registered Democrats, and have a margin of error of 5.5 percentage points.