After Nordstrom dropped Ivanka Trump's fashion line, President Donald Trump quickly tweeted his disapproval. A day later, the president was the target of venom from Meghan McCain, angry over Trump's criticism of her father, Arizona Sen. John McCain.
Different circumstances, the same lesson: Don't mess with political dads and their daughters.
For Trump, getting involved in the Nordstrom situation wasn't without risk. His tweet that Ivanka had been treated "so unfairly" — later retweeted from the official presidential account — drew the ire of ethics experts who questioned the use of his platform to comment on a family business.
But when it comes to his kids, Trump is known to be protective.
Ivanka Trump has not publicly commented on the situation. A person close to her said she did not ask him to do this and she is staying out of it because she takes seriously her pledge to separate from her business.
The president reiterated his support for his daughter in another tweet Saturday.
"I am so proud of my daughter Ivanka," he wrote. "To be abused and treated so badly by the media, and to still hold her head so high, is truly wonderful!"
The Trumps weren't the only father-daughter duo showing support this past week.
Meghan McCain sprang to her father's defense after Trump slammed the Republican lawmaker on Twitter. The president accused McCain, a decorated veteran and former prisoner of war, of emboldening the enemy for disputing the administration's insistence that a deadly U.S. military mission in Yemen was a success.
The senator did not weigh in, but his daughter tweeted: "Trump has never served. My father can't bend one of his knees or lift one of his arms above his head. I am done with this today."
These are just the latest examples of political families fighting for each other.
Before Twitter was available, President Harry Truman backed his daughter the old-fashioned way. Truman sent an angry letter to a Washington Post music critic who wrote a less than favorable review of one of Margaret Truman's concerts.
After the concert, Paul Hume wrote that she "cannot sing very well." Truman responded by sending a note to him on White House stationery, dated Dec. 6, 1950, calling it a "lousy review." He added: "Some day I hope to meet you. When that happens you'll need a new nose, a lot of beefsteak for black eyes, and perhaps a supporter below!"
Katherine Jellison, head of the history department at Ohio University, asked: "If Twitter had existed in those days, would Harry Truman have tweeted the critic instead of writing a letter?"
More recently, President Bill Clinton defended his family's decision to send his daughter, Chelsea Clinton, to a private school while he was in the White House.
At a town hall meeting in 1993, Clinton said his daughter was "not a public figure. He continued that "she does not like getting a lot of publicity. And frankly, she has more privacy and more control over her destiny where she is than she would if she were at the public school that she was also interested in attending."
Several years later, Chelsea Clinton gave a silent show of support for her father when, at the height of her parents' public marital problems in 1998, she was photographed walking between them holding both of their hands. To many, it looked as though she was holding the family together.
At other times, presidents have supported their daughters more silently. When Jenna and Barbara Bush drew some unwanted headlines for underage drinking during his time in the White House, President George W. Bush did not weigh in publicly.
These family political bonds sometimes even extend to furry friends.
In 1944, President Franklin Delano Roosevelt made a campaign speech that touched off a Republican attack that he had sent a Navy destroyer to pick up his dog Fala in the Aleutian Islands.
"I am accustomed to hearing malicious falsehoods about myself," Roosevelt said. "But I think I have a right to resent, to object to libelous statements about my dog."