Washington DC - The Supreme Court on Thursday rejected an attempt by a California man to trademark the suggestive phrase "Trump too small."

The court, in a unanimous opinion, ruled that the Patent and Trademark Office (PTO) had correctly turned down the request to trademark the slogan about Republican presidential candidate Donald Trump.

Steve Elster, who wanted to print T-shirts with the phrase, had claimed before the court that the PTO's rejection of his trademark application was a violation of his First Amendment free speech rights.

The Supreme Court rebuffed the argument, noting that the Lanham Act prohibits registration of a trademark that includes the name of a living person without their written consent.

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"Even when the trademark's message is neutral or complimentary, a person may withhold consent to avoid any association with the goods, or to prevent his name from being exploited for another's gain," Judge Clarence Thomas wrote.

Trump, a scandal-plagued former president seeking to return to the White House in November, was not personally involved in the case.

He was convicted last month in New York of falsifying business records and has also been charged with seeking to overturn the results of the 2020 election he lost to Democrat Joe Biden.

The phrase "Trump too small" arose from a 2016 Republican presidential primary debate during which Florida Senator Marco Rubio said Trump had "small hands."

"And you know what they say about guys with small hands," Rubio added in a sexually suggestive joke.

Trump, who frequently referred to Rubio during the campaign as "Little Marco," responded by saying, "I guarantee you there is no problem."

Elster's attorney had argued that the "Trump too small" phrase was "political commentary" and was meant to convey "the smallness of Donald Trump's overall approach to governing as president of the United States."