Answer by taking a quote from the following article:

Daniel Robert Graham (born November 9, 1936) is an American politician and author. A member of the Democratic Party, he was the 38th governor of Florida from 1979 to 1987 and a United States Senator from 1987 to 2005. Born in Coral Gables, Florida, Graham won election to the Florida Legislature after graduating from Harvard Law School. After serving in both houses of the Florida Legislature, Graham won the 1978 Florida gubernatorial election, and was reelected in 1982.

Graham was then elected to the U.S. Senate in 1986, defeating incumbent Sen. Paula Hawkins 55 to 45 percent. He was reelected in 1992 (over Bill Grant, 66%-34%) and 1998 (over Charlie Crist, 63%-37%) and chose not to seek reelection in 2004. Upon retiring from the Senate in January 2005, Graham had served 38 consecutive years in public office.  During his 18 years in the Senate, Graham served on the environment and finance committees, and was a founding member of the Democratic Leadership Council. He was also active on veteran's issues and foreign policy, including chairing the US-Spain Council, for which he received the highest civilian recognition for a non-Spaniard by King Juan Carlos.  Graham served 10 years on the Senate Intelligence Committee, which he chaired during and after 9/11 and the run-up to the Iraq war. He led the joint congressional investigation into 9/11. As Chairman of the Senate Intelligence Committee, Graham opposed the War in Iraq and was one of the 23 Senators who voted against President Bush's request for authorization of the use of military force. After meeting with military leaders in February 2002, and requesting and reviewing a National Intelligence Estimate, he said he "felt we were being manipulated and that the result was going to distract us from where our real enemies were". He continued to oppose the Iraq War, saying in 2008: "I'm afraid I never wavered from my belief that this was a distraction that was going to come to a bad end in Iraq and an even worse end in Afghanistan"  In 2004 Graham published Intelligence Matters: The CIA, the FBI, Saudi Arabia and the Failure of America's War on Terror. In September 2008 the book was released in paperback with a new preface and postscript.  Graham has a well-known habit of meticulously logging his daily activities (some as mundane as when he ate a tuna sandwich or rewound a tape of Ace Ventura) on color-coded notebooks, which some say may have cost him a spot on past vice-presidential tickets. The notebooks are now housed at the University of Florida library. A great advocate for his home state, Graham always kept Florida orange juice on hand in his Senate office and was rarely seen without his trademark Florida tie.

Was there any controversy involving him as a U.S Senator?