General manager Jeff Luhnow and manager Bo Porter are at odds, according to multiple major-league sources.

Porter expressed his frustration with Luhnow to owner Jim Crane in a conversation earlier this month, sources said.

Luhnow and Crane declined comment. Porter also declined comment, saying, “My focus is on managing and finishing the season strong.”

Porter’s frustration stems from a lack of input and from his belief that Luhnow engages in excessive second-guessing of his in-game management, sources said.

Losing exacerbates tension for every club, but the Astros appear to be dysfunctional on multiple levels.

Those critical of Luhnow say that he keeps a small circle, communicating mostly with director of decision sciences Sig Mejdal and others while rarely consulting the team’s on-field staff, executive advisor Nolan Ryan and special assistant to the GM Craig Biggio.

The Astros hired Luhnow in December 2011 and Porter in September 2012. The lengths of their respective contracts are not known.

Crane could attempt to broker a peace between Luhnow and Porter, and Ryan’s son -- Astros president of business operations Reid Ryan -- also could play a role in such discussions, sources said.

But perhaps it is not a surprise that the emotional Porter and deeply analytical Luhnow are proving to be an uncomfortable fit, raising questions about the team’s future leadership.

Crane expected significant progress after three straight seasons of 106 or more losses, telling reporters shortly before the season started, “I’d love to see us get to .500.”

The Astros, however, are on pace to finish 68-94 -- 26 games below .500. Only the Rangers, a team decimated by injuries, own a worse record in the AL.

In late June, Sports Illustrated proclaimed the Astros, “Your 2017 World Series champs,” citing the team’s deep collection of young talent, including three straight No. 1 picks in the amateur draft.

Since then, the Astros have failed to sign their top 2014 selection, high-school left-hander Brady Aiken, creating a firestorm that, according to sources, added to the strain within the organization.