Calgary-based Agrium on Friday suffered a setback in its bid to take over rival CF Industries.

The bid could be thwarted by CF's separate campaign to take over a third company, Terra Industries of Sioux City, Iowa.

Agrium's offer is conditional on CF dropping its bid for Terra.Agrium's offer is conditional on CF dropping its bid for Terra.

Terra shareholders voted Friday in favour of installing three CF-recommended directors to the Terra board. That increases the odds of Terra's board changing direction and recommending that their shareholders accept CF's $4.1-billion US offer.

Agrium's nearly $5-billion US offer for CF is conditional on it dropping its pursuit of Terra.

"I think that Agrium should simply take its marbles and go home. Agrium was a great company without CF and it's going to be a great company without CF in the future," said Mark Connelly, an analyst with Sterne Agee.

With files from The Canadian Press