Rep. Steve Cohen, a Democrat congressman from Tennessee, broke a fundamental rule of politics on Monday.

In a tweet attacking President Donald Trump, Cohen made reference to Trump’s son, Barron Trump.

He golfs when he could be reading or be in church or be with his family. Never see him with Barron. You’d think he’d be golfing with Dad occasionally but narcissists only engage in activities where they are the show. No movies, sports viewing either just Fox! He will start a war! https://t.co/RFuJksiQyk — Steve Cohen (@RepCohen) December 31, 2017

“He golfs when he could be reading or be in church or be with his family. Never see him with Barron. You’d think he’d be golfing with Dad occasionally but narcissists only engage in activities where they are the show. No movies, sports viewing either just Fox! He will start a war!” he wrote.

Cohen — who currently represents Tennessee’s 9th Congressional District — has long been a critic of the Republican president.

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The Monday morning tweet was in response to an earlier attack on the president’s golf outings as he vacations at his Mar-a-Lago resort for the holidays.

Sam Stein, a left-wing journalist, accused conservatives of having a double standard with Trump’s golf trips as opposed to former President Barack Obama’s golfing habits.

i sincerely don’t care that Trump plays golf. god speed. but the sheer amount he plays does spotlight how insincere Obama’s critics were about his golfing habits. here’s a little sampling of people who’ve gone suddenly quiet on the topic — Sam Stein (@samstein) December 30, 2017

“(I) sincerely don’t care that Trump plays golf. god speed. but the sheer amount he plays does spotlight how insincere Obama’s critics were about his golfing habits. here’s a little sampling of people who’ve gone suddenly quiet on the topic,” the liberal writer said.

Unlike Stein, however, Cohen felt the need to make the criticisms more personal — attacking the president’s church attendance and his relationship with his 11-year-old son.

Cohen’s tweet concluded by stating that Trump would “start a war.”

Elected to Congress in 2006, the Democrat lawmaker has been an ardent opponent of Trump since the Republican splashed into the political scene.

Cohen was one of only a few Democrat congressman who introduced five articles of impeachment in November against the president, alleging he broke federal law, according to The Daily Caller.

The Tennessee Democrat claimed at the time that the aim was simply to call for the House to begin hearings on the articles.

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“We believe that President Trump has violated the Constitution, and we’ve introduced five articles of impeachment,” said Cohen, the ranking member of the House Judiciary subcommittee on the Constitution and Civil Justice.

The articles of impeachment went on to fail in the House of Representatives.

It has long been regarded that a politician’s children are kept off limits. This courtesy transcends partisan lines.

After a controversial article criticized Barron Trump’s clothing style, former first daughter Chelsea Clinton came to his defense.

It's high time the media & everyone leave Barron Trump alone & let him have the private childhood he deserves https://t.co/Wxq51TvgDX — Chelsea Clinton (@ChelseaClinton) August 21, 2017

The tweet prompted a gracious thank you from first lady Melania Trump.

Thank you @ChelseaClinton – so important to support all of our children in being themselves! #StopChildhoodBullying https://t.co/UCUpFc5ZjR — Melania Trump (@FLOTUS) August 23, 2017

The first lady has made the fight against childhood bullying a cornerstone of her time in the White House.

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