Porter had been the Astros manager since the start of the 2013 season after being named to the position on Sept. 27, 2012 while serving as third base coach for the Washington Nationals. Adam Everett will join the coaching staff, replacing Trembley as bench coach. The remaining coaches will continue in their current roles.
The search for a new manager will begin immediately.
Lawless, who has close to 35 years of experience in baseball as a Major League player, minor league manager and coach, had served as the manager for Triple A Oklahoma City earlier this season while Tony DeFrancesco was on medical leave before returing to his role as a roving infield instructor. Everett, who spent parts of 11 seasons in the Majors as a shortstop, including seven with the Astros (2001-07), rejoined the Astros organization as a minor league infield instructor in 2013.
Below is a statement from Luhnow regarding today's decision:
"Earlier today, I informed Bo Porter that he would no longer be our manager and told Dave Trembley that he would not complete the season as our bench coach.
"Bo's passion and energy are unparalleled, and his desire to win unquestioned. This decision was not made because of our current level of competitiveness in the Major Leagues. I recognize that our win-loss record is largely a product of an organizational strategy for which I am responsible. Rather, I made this decision because I believe we need a new direction in our clubhouse.
"What we will seek going forward is a consistent and united message throughout the entire organization. It is essential that as an organization we create an atmosphere at the Major League level where our young players can come up and continue to develop and succeed. Ultimately, I am responsible for creating that culture, and I will do everything in my power to do so-even when it means making difficult moves like the one we made today.
"Moving forward, I am optimistic about the direction of our team. Our young core continues to progress, and I believe wholeheartedly that our plan-while at times challenging-is working and will bring a consistent winner to Houston in the very near future.
"We wish Bo and his family well, and feel he will be successful in future endeavors."
Astros Owner and Chairman Jim Crane also commented. "This was not an easy decision to make," Crane said. "We wish Bo nothing but the best in the future. Jeff has my full support moving forward. Our goal to bring a championship to Houston remains."