WASHINGTON — A new conservative nonprofit group scored a $1.6 billion windfall last year via a little-known donor — an extraordinary sum that could give Republicans and their causes a huge financial boost ahead of the midterms, and for years to come.
The source of the money was Barre Seid, an electronics manufacturing mogul, and the donation is among the largest — if not the largest — single contributions ever made to a politically focused nonprofit. The beneficiary is a new political group controlled by Leonard A. Leo, an activist who has used his connections to Republican donors and politicians to help engineer the conservative dominance of the Supreme Court and to finance battles over abortion rights, voting rules and climate change policy.
This windfall will help cement Mr. Leo’s status as a kingmaker in conservative big money politics. It could also give conservatives an advantage in a type of difficult-to-trace spending that shapes elections and political fights.