Hampton took an undergraduate degree in philosophy and religion from Dartmouth College, an Ivy League institution in New Hampshire, where he played for the school's D-I NCAA hockey team. He later obtained a degree in education from the University of Toronto and a law degree from the University of Ottawa. He worked as a lawyer for the Canadian Labour Congress, and for the provincial NDP government of Allan Blakeney in Saskatchewan.
Hampton sought election to the Ontario legislature under the NDP banner in the 1977 provincial election, placing third against incumbent Liberal Pat Reid and Progressive Conservative Gordon Thomson in Rainy River. He ran for the riding again in the 1985 provincial election, and lost to Progressive Conservative candidate Jack Pierce by 278 votes.
By all accounts, Hampton and Rae were not cabinet allies. Hampton disapproved of many of the Rae government's centrist policies; in particular, he opposed Rae's decision to retreat from an election pledge to introduce public automobile insurance in the province. Journalist Thomas Walkom has argued that Rae deliberately undermined Hampton's control over the Attorney General's office, staffing the ministry with bureaucrats to which he was ideologically incompatible. However, Walkom has also noted that Hampton supported Rae's decision to impose a Social Contract of wage restraints and cost-saving measures on Ontario public servants.
Following a cabinet shuffle on February 3, 1993, Hampton was demoted to Minister of Natural Resources, responsible for Native Affairs. Marion Boyd replaced him as Attorney General. The NDP were defeated in the provincial election of 1995, and Hampton re-elected over Progressive Conservative Lynn Beyak by only 205 votes.
After Rae retired from politics, Hampton became the leader of the NDP on June 22, 1996, beating Frances Lankin, who was seen as a Rae ally and whom many had considered the front-runner, on the third ballot. Leadership candidate Peter Kormos and his support generally went to Hampton rather than Lankin, which was seen as important to Hampton's victory. Tony Silipo also ran for the leadership and would become Hampton's Deputy Leader until 1999.
In the 1999 Ontario election, some progressives and union leaders, who had been a crucial source of NDP support before 1995, attempted to defeat Mike Harris, the Progressive Conservative premier, by abandoning the NDP for the Liberals. This tactical voting, commonly called "strategic voting," did not succeed in ousting the Harris government, but nearly decimated the NDP as they took just nine seats and 12 per cent of the popular vote in their poorest election showing since the 1950s. As Hampton was not judged to have been at fault, he stayed on as leader. Hampton himself faced a challenging re-election against Liberal Frank Miclash, but was able to win fairly convincingly.
Hampton endorsed Bill Blaikie in the latter's unsuccessful bid for the federal New Democratic Party leadership in 2002. This decision was unpopular with some other members of his caucus, including Deputy Leader Marilyn Churley who was a leading supporter of Jack Layton.
In Harris' second term, the government unveiled plans to privatize the public electricity utility, Ontario Hydro. Hampton quickly distinguished himself as an advocate of maintaining public ownership of the utility, and published a book on the subject, Public Power, in 2003. Harris' successor as premier, Ernie Eves, ultimately reached the decision not to sell the hydro utility.
Hampton and the NDP won only seven seats in the 2003 Ontario election, losing official party status for the first time since 1963. However, Hampton retained his seat and the party increased its share of the popular vote by 2%. After intense lobbying to lower the minimum number of seats for party status, a compromise was reached which allowed additional funding for the NDP and more inquiry opportunities during Question Period.
Ultimately, this controversy was all for nought as on May 13, 2004, the NDP regained official party status in a by-election in Hamilton East, where city councillor Andrea Horwath was elected to fill the vacancy left by the death of Liberal member Dominic Agostino. When Marilyn Churley resigned her Toronto—Danforth seat in May 2005, the NDP was granted official party status at first until the by-election, and then until the 2007 provincial election; NDP candidate Peter Tabuns won the seat.
Recent polls suggest that the NDP may at long last be recovering its early 1990s levels of support. A July, 2006 Environics poll showed the Ontario NDP with 27% popular support, it's highest level recorded since March, 1992, when Bob Rae's government was still in power. However, in the poll, the NDP still trailed the governing Liberals who received 35% support and the Opposition Progressive Conservatives who led with 36%. Other polls have shown the NDP with 20-23% support, further behind the frontrunning parties but still well ahead of the popular vote the Party received in 2003. After losing party status in two successive elections, the pressure will be on Hampton to translate the NDP's recent resurgence into more seats in the next provincial election.
The Ontario NDP increased its seat count to nine in September 2006, when well-known local United Church minister Cheri DiNovo won a byelection. The seat became vacant when Liberal MPP Gerard Kennedy resigned to seek the Liberal Party of Canada leadership.
Hampton launched the Ontario NDP's 2007 provincial election campaign at the party's Fresh Ideas New Energy January 2007 policy convention. Hampton's keynote speech focused on the party's campaign to raise the minimum wage to $10 an hour, and signalled the NDP's renewed focus on matters of economic justice. The NDP also unveiled a new logo and look.
Hampton's NDP increased its seat count to 10 in February 2007, when businessman and community activist Paul Ferreira defeated star Liberal candidate Laura Albanese in a byelection in the Toronto riding of York South-Weston. The seat became vacant when Liberal cabinet minister Joe Cordiano resigned. The NDP's campaign for the $10 minimum wage and its opposition to a controversial 25% pay raise for MPPs are cited as key factors in the upset win.
Despite several encouraging opinion polls that predicted a gain of several seats, Hampton's NDP failed to increase its seat count beyond 10 in the 2007 provincial election. While there was speculation following the election that he may retire Hampton announced at the November 24, 2007, NDP provincial council that he was staying as party leader. He announced in April 2008 that he was considering his political future, and would make an announcement later in 2008 as to whether or not he will stay on further as the party leader.
On June 14 2008, Hampton announced that he is not going to stand for re-election as party leader at the March 2009 party convention. He indicated, however, that he will continue to serve as the MPP for Kenora—Rainy River at least until the 2011 election.