Virginia Del. David L. Englin (D-Alexandria) waded into the heated Democratic primary contest in the 31st state Senate District on Monday, endorsing Jaime Areizaga-Soto for the post and attacking “party bosses” for backing Barbara Favola instead.

The 31st district — which is being vacated by retiring Sen. Mary Margaret Whipple (D) and now stretches from Arlington to eastern Loudoun County — is playing host to one of the nastiest intraparty contests in the state. Areizaga-Soto, an attorney, and Favola, an Arlington County Board member, have been trading barbs and accusations for weeks.

While Areizaga-Soto has sought to portray himself as the more liberal of the two candidates and has courted the party grass roots, Favola has the backing of much of the local Democratic establishment — getting endorsements or campaign contributions from Whipple, Del. Bob Brink (D-Arlington) and Senate Majority Leader Richard L. Saslaw (Fairfax).

That support for Favola has angered some backers of Areizaga-Soto, who believe that party leaders have unfairly sought to stack the deck for Favola and muscle other candidates out of the race.

Englin, whose wife is a paid consultant for Areizaga-Soto, said he had planned not to comment on the contest, but “my simmering anger at how my own party’s leaders in the Virginia Senate are handling this race has boiled over, and I can no longer remain silent.”

Noting that Areizaga-Soto would be the first Latino elected to the Virginia Senate if he won, Englin said party leaders were opposing him “because he has the nerve to seek his party’s nomination against their hand-picked choice. They are so incensed by his candidacy that they have spent tens of thousands of dollars to attack him that could otherwise be used to defend their tenuous Democratic majority.”

Englin is particularly upset by the behavior of Whipple, who released a letter last week saying that Areizaga-Soto was essentially just an “intern” for her in Richmond even though she had previously referred to him as a “policy adviser” — the title Areizaga-Soto has been using to describe his service.

Favola’s campaign suggested that Englin might not be the most unbiased observer of the race.

“While we respect the Delegate’s right to endorse whoever he sees fit, it’s important to note that his wife has a financial interest in the campaign,” said Favola spokeswoman Mary Lawson.

The primary is Aug. 23.