Former President George W. Bush penned a fundraising letter sent out Thursday on behalf of his brother Jeb Bush, a candidate for the 2016 Republican presidential nomination.

George W. Bush noted in the email sent to Jeb Bush's campaign list that he "rarely" pens such letters, adding that it is "a consequential time" in the U.S. and "we need a strong leader."

"My brother will be a tremendous President," the 43rd president wrote of the former Florida governor. "He’s got a tough road ahead — take it from someone who's been there."

The email, which requested donations in amounts of $25, $50 or $100, is the first of its kind from the former president on behalf of his brother's White House bid.

George W. Bush said earlier this summer that he was "not gonna be a surrogate," but the email signals the campaign's willingness to utilize the elder Bush.

The former president has been out of office for more than six years, but the debate over his legacy, in particular the Iraq War, has flared up amid his brother's campaign.

Democrats have tried to link him with the policies of his brother and father, former President George H.W. Bush.

Jeb Bush has struggled at times to show both support for his brother and his father, while also insisting he is his "own man."

Former Presidents George W. Bush and George H.W. Bush and Jeb Bush's mother, Barbara Bush, will appear at a campaign donor retreat in late October, The Washington Post reported Thursday.