In campaigns, we have a saying: If your opponent is hanging himself, give him more rope. In the week after the convention, while Mrs. Clinton was touring Western Pennsylvania and Eastern Ohio, talking about her plan to create jobs through new investments in infrastructure and advanced manufacturing, we tried to get out of the way of the negative coverage of Mr. Trump and his outrageous comments about Mr. Khan.

But the result was that people heard his message, not ours. So much so that after the election, some people thought Mrs. Clinton never talked about people’s economic lives. But she did. It just went into the black hole of the Trump Trap.

Mr. Trump never attacked Cheryl Lankford or the other people suing Trump University. Instead, he disparaged the Latino judge in the case, so we spent a week talking about how racist he is, not about how he had cheated working people. He didn’t attack Mrs. Clinton the week after the convention for her infrastructure plan or her advanced manufacturing plan; he hurled attacks at the Khans.

Mr. Trump will say and do things that demand a response from anyone who values decency and morality. The result is that he decides what gets attention — and he’s not held accountable.

So what do we do?

First, Democrats have to call these distractions what they are: distractions. A speech denouncing his name-calling will result in headlines about name-calling. That, as we learned, does not help voters understand what progressives believe and who we are fighting for. We need to demand answers for the administration’s assault on health care coverage, its corruption and its bilking of middle-income taxpayers.

Second, the media needs to realize that the game has changed. Just because the president says or tweets something outrageous doesn’t mean it’s news. Just like Facebook and Twitter have a responsibility to root out harassment and impostors from their platforms, the news media has an obligation to report responsibly on the president. Sometimes stupid insults are just that and should be ignored. That will mean lost revenue, but it’s a price worth paying.

Third, we Democrats have to pick fights that highlight Mr. Trump’s malfeasance. When the president seeks to take away health insurance from seniors or people with cancer, we can’t let that go unnoticed. Some Democrats seem more interested in fighting one another on health care than fighting the Republican Party — let’s arm wrestle one another when we actually have a majority to pass a new law. In the meantime, let’s help voters understand why a change is so badly needed.