Senator Bernie Sanders, I-Vt., will soon break ties with the Democratic Party and run for president as an independent, which would "all but guarantee a catastrophic split in the Democratic vote and ensure a Republican victory," according to journalist Ed Klein, who cited confidential inside sources.

Several of Sanders' top campaign officials told Klein "the 73-year-old leftwing firebrand is convinced the fix is in to give the Democrat nomination to Hillary - unless she implodes, at which point the party will line up lockstep behind Biden."

"These sources say Sanders believes that despite his ever-growing crowds of fired-up supporters, he'll never overcome Hillary's - or, for that matter, Biden's - advantage in money, organization and endorsements," Klein wrote.

One source told Klein that Sanders believes Clinton is "owned by Wall Street and is a hawk," adding that there is "no way he's going to come to an accommodation with her. He is not in this to compromise."

Sanders hasn't decided when to announce that he will run as an independent but will probably make the announcement once Clinton "starts piling up delegates with the help of Wall Street money and her formidable ground operation," according to the source.

If Sanders does decide to launch an independent bid, it would be a complete reversal from statements he made in late July, when Sanders explicitly vowed not to run as an independent if he didn't clinch the Democratic nomination out of fear that he would be responsible for electing "some right-wing Republican president," as The Hill reported.

Klein's source continued, saying, "Right now, things are going great and he very well may upset Hillary in the New Hampshire primary."

The latest New Hampshire data from Public Policy Polling has Sanders leading Clinton by a margin of 42 percent to 35 percent, a significant turnaround since a previous April survey, and the second survey released this month showing Sanders ahead of Clinton in the Granite State, as HNGN previously reported.

"The main story in New Hampshire is how universally popular Sanders has become with the Democratic electorate," Public Policy Polling said. "Seventy-eight percent see him favorably to only 12 percent with a negative opinion - that makes him easily the most popular candidate on either side with their party's voters."

"Meanwhile Hillary Clinton's favorability numbers have taken a little bit of a hit - she was at 78/10 with Democratic primary voters in April, but now she's at a 63/25 spread."

Clinton's favorability ratings have also taken a dive in a few national polls, including her trustworthiness and honesty ratings. Her reputation has been suffering due to a number of scandals, most recently her exclusive use of a private unsecured email system during her tenure as secretary of state, which investigators say was used to send and receive highly classified data.

However, Sanders still trails Clinton on the national level among likely voters, 48.7 percent to 27.7 percent, according to a RealClearPolitics average of polling data, but the self-described democratic socialist continues to gain steady ground.

"Bernie's polling has shown that he has a tidal wave of support among people across the country who have never or seldom voted," Klein's source said. "They'll come out for him and pull the Independent Party lever."