WASHINGTON — Liberal House Democrats, struggling to combat President Trump’s stonewalling of congressional oversight, have come out by the dozen in recent days to endorse a new strategy to secure the information that they say they need: opening an impeachment inquiry.

Supporters of an inquiry argue that they are not necessarily seeking the president’s ouster but instead are pursuing a legal strategy — warranted by the stakes — to try to break Mr. Trump’s blockade of nearly every document and witness that Democrats have requested since the release of the redacted report by the special counsel, Robert S. Mueller III, in April. Opening an investigation, they say, could increase Democratic chances of winning court orders to require compliance with House subpoenas.

But others are wary, saying it would be politically risky; impeachment implies an effort to remove the president from office, and Mr. Trump is primed to try to exploit any such effort politically. On Thursday, he called impeachment a “dirty, filthy, disgusting word.”

Here’s what you need to know about how impeachment inquiries work.

What is impeachment?

The Constitution permits Congress to remove presidents before their terms are up if enough lawmakers vote to say that they committed “treason, bribery, or other high crimes and misdemeanors.”