When Vice President Joe Biden appeared on The Late Show last week, Stephen Colbert’s first question was about authenticity. “You’re not a politician who’s created some sort of facade to get something out of us,” Colbert said. “We see the real you. How did you maintain your soul in a city that is so filled with people who are trying to lie to us?”

Our Brand Is Crisis is about the people who lie to us. Specifically, it’s about political operatives who sell their services — and their souls — to the highest bidder. To these men and women, elections are not about ideology, they are about wins and loses. In the film — which is, according to the credits, “suggested by” the 2005 documentary of the same name by Rachel Boynton — the operatives take things one step further by plying their trade abroad, where it’s even easier to disassociate themselves from the potentially catastrophic consequences of their actions. When the election’s over they just pack up and move on to another country and the next campaign.

Not everyone gets out unscathed, though; Sandra Bullock stars as “Calamity” Jane Bodine, once a hugely successful election consultant with a reputation for working miracles on lost causes, now a hermit living in isolation. Somewhere along the way, the stress of her job became too much to bear, and Jane had a whopper of a breakdown. When two more freelance campaign managers (Ann Dowd and Anthony Mackie) track her down at a remote house in the woods, she’s retired and finally at peace spending her days glazing pottery. But Jane, who clearly has an addictive personality, can’t resist the high that comes with her old job, and she unwisely agrees to go back to work guiding the underdog in the upcoming Bolivian Presidential election.

Her client is an unpopular former president named Castillo (Joaquim de Almeida); when Jane signs on, he’s languishing in fourth place, primarily because his chief rival is being coached by Jane’s chief rival, a Machiavellian mastermind named Pat Candy (Billy Bob Thornton). Jane and Pat have a long-standing competition; she claims that they’ve been on opposite sides of “three or four” previous elections, and she’s lost three or four of them. This time, she insists, will be different.

Any time Bullock and Thornton share the screen, Our Brand Is Crisis jumps to life. The two stars share palpably abrasive chemistry.They love to hate each other, and their bilious banter recalls the old battles of the sexes between Spencer Tracy and Katharine Hepburn. Their tête-à-têtes are spectacular — but that’s about all that’s spectacular about Our Brand Is Crisis, which is otherwise a pretty tepid satire of modern political culture.

Director David Gordon Green and producers George Clooney and Grant Heslov deserve a certain amount of credit just for getting this unusual movie made by a major studio in the first place. Our Brand Is Crisis is the rare mainstream film to consider the role of America in Latin American politics, and to feature both the International Monetary Fund and Sandra Bullock’s naked butt. It’s refreshing to see Hollywood tackle these subjects at all, and Green’s offbeat sense of humor compliments Peter Straughan’s cynical screenplay. But the film’s critique of interventionism and the win-at-all-cost campaigning never goes beneath the surface, and its simplistic ending feels like a betrayal of the rest of the movie’s values.

The supporting cast (which also includes Zoe Kazan and Scoot McNairy) are most squandered in meaningless roles, but Thornton and Bullock are both tremendously fun to watch. As the self-destructive Jane, Bullock continues her mid-career renaissance with another impressive and egoless performance that sees her ranging from laugh-out-loud physical comedy to soul-crushing despair. She’s so compulsively watchable that she makes it easy to forgive a lot of Our Brand Is Crisis’ shortcomings.

In response to Stephen Colbert’s question on The Late Show, Vice President Biden said, “Would you want a job that in fact every day you had to get up and modulate what you said and believed?” Bullock and Thornton’s clients will modulate everything about themselves to get what they want. The worst thing you can say about Our Brand Is Crisis is that it clearly will too.