As an example, let's say a new law is currently discussed in US Congress that would boost the production of widgets if passed. Acme corporation makes a lot of widgets and wants the law to succeed. Would it be legal for Acme's CEO to publicly promise to donate $1 million in support of every Congress member who votes in favor of the law? Obviously there are limits to how much a corporation could give to a candidate but this can by side stepped by donating to a Super PAC which will run ads to support said candidate.
As a corollary, would it be legal to promise to donate $1 million to a Super PAC opposing the candidacy of every Congress member who votes against the law? So if the Republican Senator from Florida votes against widgets, Acme corporation vows to donate $1 million to the Democratic candidate for Senate in the next election cycle.