Oakland Raiders running back Marshawn Lynch sits on a cooler during the national anthem before an away game against the Miami Dolphins at Hard Rock Stadium on Nov. 5. (Jasen Vinlove/USA Today Sports)

President Trump expanded his attack on the patriotism of protesting NFL athletes by introducing a new topic into the conversation: Mexico.

Since his attacks on NFL players intensified while he was campaigning for the Alabama Senate race, Trump has tried to paint the athletes as disloyal to America — and, just as important, to American citizens.

A frequent pivot of the president's was to focus on how disrespectful he thinks the protests are to veterans and soldiers.

But in the past month or so, the sincerity of Trump's commitment to soldiers and veterans has been called into question, given some of his recent actions and policy decisions.

The president's much-criticized response to the deaths of four U.S. soldiers in Niger led some Americans to conclude that Trump uses the military as a weapon against political opponents, be they transgender Americans, undocumented immigrants or athletes.

A federal judge said this month that Trump’s proposed transgender military ban stigmatizes an entire group of people and probably is already having a negative effect on active-duty service members trying to plan for future military assignments.

And The Post's Monkey Cage wrote about a recent Military Times poll that claimed that “although active-duty service members support Trump slightly more than civilians do — though not by much — more than half of the officer corps sees him unfavorably.”

And an increasing number of veterans refuse to allow themselves to be pitted against athletes protesting racism.

But in his most recent comments wading into the NFL protests discussion, Trump attempted to cast the patriotism of one frequent critic of his into question by suggesting that he is more loyal to Mexico than to the United States.

In an early-morning tweet Monday, the president wrote: “Marshawn Lynch of the NFL’s Oakland Raiders stands for the Mexican Anthem and sits down to boos for our national anthem. Great disrespect! Next time NFL should suspend him for remainder of season. Attendance and ratings way down.”

From the day Trump launched his presidential run, he sought to portray Mexico as a threat to America's safety.

He said:

“When Mexico sends its people, they’re not sending their best. They’re not sending you. They’re not sending you. They’re sending people that have lots of problems, and they’re bringing those problems with us. They’re bringing drugs. They’re bringing crime. They’re rapists.”

And on multiple occasions since that day more than two years ago, when Trump wants to talk about making the United States safe from criminal activity, he points to Mexico.

Or when he wants to address drug-trafficking and related crimes.

Or even when he wants to talk about the harm done to the U.S. economy.

Trump has not gone on the record to seriously engage the concerns of the athletes who have repeatedly described the reasons behind their protest. But for some of his supporters, the president doesn't have to. Multiple polls show that support for the protests are low among many Americans.

So is Trump's overall approval rating. But in a news cycle highlighting the expanding investigation into the relationship between Russia and the Trump campaign, most Americans' belief that the GOP tax plan only benefits the wealthy, and Trump's continued support for a GOP Senate candidate accused of sexually assaulting minors, appealing to the “cultural anxiety” of his base may be the president's effort to win some favorability points with his supporters.