WASHINGTON — House Democrats sent bills to the Senate only to watch them wither under dismissive Republican leadership on scores of occasions this year. They did so yet again on Wednesday, but this moment carried a weight all its own.

This was no election security measure or minimum wage increase or drug pricing legislation. It was two articles of impeachment against Donald John Trump, a historic condemnation of the 45th president of the United States, a polarizing figure who nonetheless remains popular in the districts of dozens of Democrats who provided the party the House majority that enabled the action against him.

The effort to remove the president from office carries inherent political risks. But they are particularly wrenching for Democrats knowing that their votes will not, barring some entirely unexpected turn of events, lead to a Senate conviction of Mr. Trump and his immediate departure from the White House. They are putting themselves on the line not for an outcome but for a principle.

In the end, Democrats concluded, with almost no defections even from the moderates whose re-elections will be most in jeopardy, that they could not let Mr. Trump’s conduct in encouraging Ukraine to investigate a political rival go unpunished even if it cost some lawmakers their seats. And history suggests that high-profile partisan House initiatives that go on to die in the Senate can yield just that outcome.