When in doubt, don’t touch a thing.

That’s the approach politicians took Tuesday night when city council voted to slam the brakes on a potential rejigging of development charges in downtown London — a proposal that sparked a firestorm from major builders who warned it may force them to leave town.

Following a debate that was ugly even by the standards of political infighting, politicians hit pause on a public discussion of the proposed changes in an effort to ease developers’ concerns.

“I don’t like the tone I’ve seen tonight,” Coun. Nancy Branscombe said, noting it indicated to her industry resistance could be just as divisive.

Branscombe was in the middle of the fiery discussion that reached its low point when Coun. Stephen Orser fired insults at three colleagues — Branscombe, Joni Baechler and Paul Hubert — in a furious speech.

The source of Orser’s angst? Medallion, a builder in Old East Village, joined Rygar, which is planning a 33-storey downtown highrise, in warning any changes to development charges (which are waived for residential construction in both areas) may nix their future projects.

Orser’s barb at Branscombe suggested she was incapable of doing her council work while preparing to run for provincial office in London North Centre. Shortly thereafter, Mayor Joe Fontana called for a five-minute break to ease the tension.

As politicians walked away, Branscombe told Orser: “You are so full of s---.”

The controversy surrounds a possible change to the program that waives development fees in the core and Old East. It would potentially be replaced with one that reimburses builders with grants for some, or all, the development charges they pay.

Rygar, whose $80-million, 33-storey highrise would be the tallest building in London, warned in a letter that the change created uncertainty that may derail their entire project.

“The impact of development charges will result in the development not proceeding,” Rygar’s lawyer, Alan Patton, wrote.