ROCHESTER — A mere three votes separates the two Republicans hoping for the party endorsement for U.S. Senate.

An eighth ballot conducted Saturday showed St. Louis County Commissioner Chris Dahlberg’s lead over investment banker Mike McFadden eroding. What had been a 10 percentage point advantage in the wee hours was down to a negligible edge. Another round of voting was under way.

There was a chance the convention could deadlock, in which no endorsement would be awarded. McFadden says he’s running in an August primary no matter what. Dahlberg was banking on the endorsement to carry him over the better-funded rival.

The eventual nominee will take on Democratic Sen. Al Franken, a first-termer who knocked off a GOP incumbent six years ago.