E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
When the Roman senate wanted a law to be passed, they asked the people to give their votes in its favour. The Latin for this is rogre legem (to solicit or propose a law). If they wanted a law repealed, they asked the people to vote against it; this was abrogre legem (to solicit against the law).