But the buyback tax, which Democrats have been contemplating for months, has been relatively uncontroversial — at least for a tax increase. That’s probably because it is so small.

“It’s not like business endorsed this, but they also didn’t lay across the train tracks to try to stop it,” said Todd Metcalf, a former top Senate tax aide now at the consulting firm PwC.

“This is the lowest hanging fruit.”

The swap will not only help secure Sinema’s support. It will also allow Democrats to say they are raising taxes on the well-to-do while scratching their long-standing itch to do something about corporate stock repurchases. Democrats were infuriated when, in the wake of Republicans’ 2017 tax cuts, many companies used their savings to buy back stock, enriching shareholders.