Kenneth Baer, a former Obama Administration official, runs Crosscut Strategies; Jeff Nussbaum is a partner at West Wing Writers. Together, they oversaw the speechwriting operation at the 2016 Democratic convention and were once speechwriters for Vice President Al Gore. Baer tweets at @KennethBaer. Nussbaum, at @JeffreyNussbaum.

How can Hillary deliver the knockout punch Monday night?

She needs to follow the lead of a 76-year-old former amateur boxer, and hit Trump where it hurts: his pocketbook.

A little over a week ago, that ex-pugilist, Senator Harry Reid, leveled a blistering attack on Donald Trump as a “scam artist” who “rips off working people” and is hiding his tax returns, playing footsy with Vladimir Putin, and running a fake charity all to enrich himself.

Trump’s response? Silence.

It’s amazing to think that there’s anything that will quiet Trump, but after examining the political campaign to date, it’s clear that Donald Trump is well aware of what attacks hurt him, and which ones don’t. Trump’s tell is simple: he ignores the attacks he can’t parry, the ones that could open a conversation that would hurt him with the voters who (currently) support him most strongly.

Since the general election began in June, Trump has consistently ignored attacks on his business record and economic policies. He even has made outlandish statements to affirmatively shift the debate – and 24-hour-a-day cable TV coverage – away from these attacks precisely because they are his Achilles’ heel with the constituencies at the heart of his coalition: the white working class.

Look at the most sustained critique of Trump to date, the Democratic convention held in July, and how Trump reacted.

Senator Cory Booker exposed how Trump’s Atlantic City bankruptcies allowed him to walk away with an “incredible” amount of money, but devastated workers and small businesses. Trump’s tweeted response: “If Cory Booker is the future of the Democratic Party, they have no future!”

Senator Elizabeth Warren defied anyone to find an example of a time that Donald Trump helped working people. Trump’s response, “Pocahontas bombed last night.”

Vice President Joe Biden ripped into Trump for being blind to the needs of the middle class. Trump responded by calling Biden “not very bright.”

When Queens Congressman Joe Crowley, who lost a cousin in the 9/11 attacks, pointed out that Trump found a way to take a tax credit intended to help small businesses affected by the attacks (Trump isn’t, and wasn’t) get back on their feet, Trump was silent.

The same was true for attacks on Trump’s outsourcing, his belief that the federal minimum wage is too high, his eponymous “university” ripping off veterans, or his debt-ballooning tax cuts that largely benefit the extremely wealthy.

But when the Muslim-American father of an Army officer killed on the battlefield in Iraq questioned his patriotism and knowledge of the Constitution, Trump pounced. At the time, commentators saw this as a massive mistake as the furor dominated the coverage coming out of the Democratic gathering and resulted in Trump being denounced even by some Republicans.

Yet, as strange (and odious) as it may seem, it was vintage Trump. It was his opening to move the conversation away from his business record and his economic policies, and onto cultural identity issues that resonate with his base.

Recent polling shows why this makes sense for Trump. According to the latest NBC/Wall Street Journal poll, only 27 percent of those surveyed said that Trump’s “language and comments about women, immigrants, and Muslims” is a major concern. Moreover, 82 percent of voters who would consider voting for Trump – according to a recent Kaiser Family Foundation/CNN poll – say Muslims immigrants to the United States increase the risk of terrorist attacks, and 62 percent of Trump supporters said that Latino immigrants take jobs away from Americans.

Trump supporters are also profoundly alienated from the political establishment. A whopping 93 percent of them say that they feel poorly represented in Washington. They see Trump as an honest outsider who is on their side and whose success in business will transfer to the management of the economy (whose current state they also see as negative and for which they overwhelmingly blame the federal government).

Therein lies the power in the Reid punch. If one can paint Trump as dishonest, an insider who plays the system to benefit himself and also will do nothing for the white working class just as they perceive the rest of the political establishment, then the bottom will fall out of the Trump candidacy.

Despite the tightened horse-race numbers, there are signs that this is happening. In the NBC/WSJ poll conducted in June, Trump held a 10-percentage-point lead over Clinton on who people preferred on the economy; in the latest poll; that lead is now down to 5 points. Similarly, Trump’s 16-point lead on being seen as “honest and straightforward” is now down to 10 points (41 to 31 percent) in the latest NBC/WSJ poll.

Some of this may be attributed to the paid media the Clinton campaign is running virtually unanswered that does jab Trump on the economy. This includes an ad running in seven swing states featuring a U.S.-based shirt manufacturer blasting Trump for making his branded clothes overseas as well as one that features her economic plan.

As the candidates head into Monday, though, Clinton needs to follow Reid’s lead, and lean into the argument that Trump is a fraud and not on the side of the working class. As we have seen so far, that is the left hook that will lay Trump out on the on mat.