The numbers are stark: Among registered voters in a Politico/Morning Consult poll at the end of May, 43% want Congress to begin impeachment proceedings against President Trump, up from 38% the week before.

But experts say the polls may mean less than they appear to show.

Three polls by CNN/ORC showed roughly similar numbers of adults—about 30%—wanted to impeach President Clinton in 1998, President Bush in 2006 and President Obama in 2014, even though the presidents were in very different circumstances. And Gallup polls from the Watergate era show a clear majority of Americans didn’t support impeaching Nixon and removing him from office until August of 1974—the same month he resigned.

One problem is that pollsters don’t regularly ask about impeachment, so it’s hard to gauge how many respondents may be using support for impeachment simply as a way of registering disapproval, says NBC/Wall Street Journal pollster Peter Hart.

“What it says to you is basically the electorate doesn’t fully understand impeachment,” he told TIME. “Their understanding of impeachment is I’m sending a message of disapproval.”

Barbara Perry, presidential studies director at the University of Virginia’s Miller Center, notes one other huge problem: the House of Representatives is in charge of deciding whether to begin impeachment proceedings.

“This is a national poll,” she said. “We say ‘Well it looks like [support for beginning impeachment proceedings] is ticking up, 43% of the people want to move forward with impeachment proceedings.’ Well, districts that are rock-ribbed Republican and probably pretty rock-ribbed Trump, aren’t those congressman just going to say, ‘Well, that’s a national poll?’”

Perry argues that polls of individual congressional districts—which don’t exist—would be better indicators of the probability that the House will go forward with an impeachment vote.

Barring that, she said it could be helpful to look at the partisan breakdown of the impeachment polls conducted so far. The numbers there don’t indicate that the Republican majority in the House would be interested.

In the most recent Politico/Morning Consult poll, conducted from May 25 to May 30, just 15% of Republicans support the House beginning impeachment proceedings (compared to 38% of independents and 71% of Democrats who back an impeachment vote).

“The partisan polling is more nuanced than a national poll,” Perry argues. “But certainly a poll by party gives you a sense of how few Republicans are in favor of moving towards impeachment. Republicans are asking themselves, ‘If people in my party don’t want this, why would I do this?’”

However, Allan Lichtman, history professor at American University and author of “The Case for Impeachment”–a book that argues for impeaching Trump–contends the polls are noteworthy because of their timing.

“I think the polls matter a great deal,” Lichtman argues. “You’re talking about [a poll being taken] just a few months into Trump’s presidency. If representatives want to survive they need to respond to the needs of the American people.”

But Perry believes that, despite its timing, the national polls do not indicate the House is close to impeaching Trump.

“All of the polling so far does not indicate a move in the direction of beginning impeachment,” added Perry. “Unless Trump does something so egregious as to put in danger the re-election of a House member or a member of the Senate, a Republican House and a Republican Senate right now would be unlikely to impeach Trump.”

Get our Politics Newsletter. The headlines out of Washington never seem to slow. Subscribe to The D.C. Brief to make sense of what matters most. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Jack Brewster at jack.brewster@time.com.