The Rev. Jesse Jackson and his son, former U.S. Rep. Jesse Jackson Jr., have joined the effort to persuade President Donald Trump to pardon imprisoned former Gov. Rod Blagojevich.

The father and son sent a joint letter dated July 12 to the president pleading for Blagojevich’s full pardon and release, writing that “we agree with your assessment that Mr. Blagojevich’s sentence of 14 years was both unfair and unnecessary,” according to a copy of the letter provided by a Rainbow PUSH Coalition spokesman.

“We stand with this family as they seek a full pardon for a father and husband that has served most of a sentence that was far longer than the offense deserved,” the Jacksons wrote.

The letter is the latest attempt to end Blagojevich’s federal prison sentence, which began in 2012. Blagojevich’s wife, Patti Blagojevich, has made several appearances on FOX News and sent tweets urging the president to clear her husband’s name.

Patti Blagojevich read a letter from her husband at an event Saturday at Rainbow PUSH that commemorated the 20th anniversary of the Rev. Jackson and her husband’s trip to Belgrade to free U.S. servicemen captured by Yugoslavian forces.

“I will always be grateful for the opportunity I had many years ago when I joined Reverend Jackson in securing the release of our soldiers being held as POWs during the war with Yugoslavia,” the former governor and congressman wrote.

Rod Blagojevich was convicted of attempting to sell Barack Obama’s U.S. Senate seat that was vacated when Obama won the 2008 presidential election.