In a major jolt to the Democratic primary race for governor, former Newton mayor Setti Warren has abruptly ended his campaign, saying he faced insurmountable financial hurdles in trying to unseat Governor Charlie Baker. In an interview with the Globe on Wednesday, Warren said he would e-mail supporters Thursday morning explaining his decision to end the campaign. With only $51,644 in his account after a year of campaigning, Warren said that he did not have the resources to take on the popular Republican, who has a $7.9 million campaign account and consistently high standing in public polls.