TRENTON -- Kerry, Biden, Gore, and now Obama.

Former President Barack Obama will travel to Newark on Thursday to stump for Democratic nominee for New Jersey governor Phil Murphy -- his first campaign appearance since leaving office in January.

Obama will join Murphy at the Robert Treat Hotel in the afternoon for what Murphy's campaign is billing a "canvass kickoff with grassroots supporters." Attendees are allowed by invitation only.

The 44th president is the latest in a string of high-profile Democrats hitting the campaign trail for Murphy in the final few weeks of the race against Republican nominee Kim Guadagno to succeed Gov. Chris Christie.

John Kerry, who served as U.S. secretary of state under Obama, appeared with Murphy at a Clifton VFW last Tuesday. Joe Biden, who was Obama's vice president, spoke at a rally in Edison last Thursday. And former Vice President Al Gore headlined a rally in Ocean Township on Sunday.

Murphy, a former U.S. ambassador to Germany and ex-Goldman Sachs banking executive, leads Guadagno, the state's lieutenant governor, in all polls. But recent surveys have showed the race tightening.

New Jersey is one of only two states to hold a governor's race this year, along with Virginia. The elections are the first chance for Democrats to test their prowess in the wake of Donald Trump's presidential victory.

Murphy spent years as a top Democratic fundraiser, serving as finance chair of the Democratic National Committee from 2006 to 2009. After Obama was elected president in 2008, he named Murphy America's ambassador to Germany in 2009 -- a position Murphy held until 2013.

Obama's appearance will come a day after Murphy and Guadagno face off in their second and final televised debate. The two will battle Wednesday at 7 p.m. at William Paterson University in Wayne.

Election Day is No. 7. There are also five third-party or independent candidates in the race.

Brent Johnson may be reached at bjohnson@njadvancemedia.com. Follow him on Twitter @johnsb01. Find NJ.com Politics on Facebook.