A majority of Democrats in the early voting states of Iowa, New Hampshire, and South Carolina believe President Donald Trump should be sent to prison—not merely impeached—for his conduct in the White House.

That's according to a new poll released Monday by data company Optimus and the Republican firm Firehouse Strategies. The survey found that 53 percent of likely 2020 Democratic primary voters in Iowa, 50 percent in New Hampshire, and 54 percent in South Carolina agree with the statement, "President Trump should not only be impeached, but also imprisoned."

"Most Democratic voters think Donald Trump belongs in prison, not the Oval Office," said Firehouse Strategies in a summary of the poll results.

The survey also found that support for impeachment grew rapidly following news of the whistleblower complaint about Trump's effort to pressure Ukraine to investigate former Vice President Joe Biden.

"In July, in the wake of Robert Mueller's testimony on Capitol Hill, we found support for impeachment among Democratic primary voters at 60 percent in Iowa, 54 percent in New Hampshire, and 62 percent in South Carolina," Firehouse Strategies said. "This month, support for impeachment stands at 79 percent in Iowa, 75 percent in New Hampshire, and 72 percent in South Carolina."

Biden, Sen. Bernie Sanders (I-Vt.), and Sen. Elizabeth Warren (D-Mass.)—the three top-polling Democratic presidential candidates in Iowa, New Hampshire, and South Carolina—have each expressed support for impeaching the president.

The Firehouse poll comes a week after a Washington Post/Schar School survey found that 60 percent of Americans voters overall support the impeachment inquiry House Democrats launched last month.