It’s common knowledge that there’s no love lost these days between House Speaker Gordon Fox and his fellow Democrat South Kingstown Rep. Spencer Dickinson. Now Dickinson is backing up his enmity with cash.

Dickinson spent $3,820 of his own money this week on an independent expenditure targeting Fox in House District 4, according to a campaign finance report filed Thursday with the R.I. Board of Elections.

Dickinson reported spending $1,000 with Checkmate Consulting Group, an East Greenwich firm known for producing campaign mailers; $660 at Staples; and $2,160 with the postmaster, all presumably to send campaign literature to voters in the Fox-Binder race.

The speaker’s office led an unsuccessful push to defeat Dickinson in the September primary, which led Dickinson to send his constituents a scathing public letter [pdf] describing Fox as “a dictator.” In recent weeks, Dickinson has endorsed and stumped for Mark Binder, the independent who is giving Fox an unexpectedly strong challenge on Providence’s East Side.

Update: Fox isn’t taking this lightly. The speaker’s campaign filed a campaign finance complaint Friday with the Board of Elections arguing Dickinson isn’t allowed to spend more to help Binder because he already gave Binder’s campaign the maximum legal donation of $1,000.

“There is nothing independent about his illegal contribution to the Binder campaign,” Fox spokesman Bill Fischer said in a statement. “This is a clear case of collusion between Rep. Dickinson and the Binder campaign and it violates state law.”

Fox’s lawyer argues that Dickinson’s $3,820 is a coordinated expenditure, rather than an independent expenditure, under Rhode Island law.

• Related: Watch a Newsmakers debate: Fox vs. Binder (House District 4) (Oct. 21)