By Scott Malone
BOSTON (Reuters) - Voters in five East Coast states head to the polls on Tuesday for wide-open gubernatorial primary elections in Massachusetts and Rhode Island while Republicans in New Hampshire and Delaware will pick challengers to incumbent Democratic U.S. Senators.
In Massachusetts, voters could set the stage for a general election matchup between state Attorney General Martha Coakley, a Democrat, and Republican businessman Charlie Baker, who is making his second run at the office after failing in a bid to unseat Democrat Deval Patrick in 2010.
Patrick has opted against seeking a third term in office.
Both Coakley and Baker face competitive primaries in their own right, with the other Democratic candidates including State Treasurer Steve Grossman and healthcare policy expert Don Berwick and Baker's Republican rival, Mark Fisher, who owns a small manufacturing company.
While polls have consistently shown Coakley leading her primary rivals and ahead of Baker in a theoretical general-election matchup, a key question will be whether she could win the support of Grossman voters if she wins the primary, said Peter Ubertaccio, chairman of the political science department at Stonehill College in Easton, Massachusetts.
Coakley stunned Massachusetts Democrats in 2010 when she lost an off-cycle race for the U.S. Senate seat held by Edward M. Kennedy for a half century to Scott Brown, then a little-known Republican state legislator.
"Some Grossman voters have a longstanding gripe against Coakley for the 2010 loss," Ubertaccio said. A late August poll by WBUR radio and MassInc Polling Group found that 42 percent of Grossman supporters planned to vote for Baker, a moderate on social issues, if Coakley wins the primary.
Brown will be facing his own primary on Tuesday as he seeks the Republican nomination to run for Senate in New Hampshire, where he moved late last year after losing his first re-election bid in Massachusetts.
New Hampshire voters will also pick a Republican challenger to incumbent Governor Maggie Hassan, with businessman Walt Havenstein and Tea Party activist Andrew Hemingway the top contenders in that primary, according to polls.
Voters in Rhode Island, where Governor Lincoln Chafee last year said he would not seek re-election, also face two competitive primaries.
On the Democratic side, polls show state Treasurer Gina Raimondo and Providence Mayor Angel Taveras leading a four-way race, while Republicans will pick between Cranston Mayor Allan Fung and software executive Ken Block.
Delaware voters also face a Republican U.S. Senate primary, with businessmen Carl Smink and Kevin Wade looking to take on Democratic U.S. Senator Chris Coons in November.
New York voters also face a choice of whether to back Fordham University law professor and former Occupy Wall Street activist Zephyr Teachout, who is seeking to wrest the Democratic nomination to run for governor from Andrew Cuomo, the popular incumbent.
(Reporting by Scott Malone; Editing by Sandra Maler)