The Houston Astros (42-32) are four games ahead of the Texas Rangers for first place in the AL West and general manager Jeff Luhnow has made it known the team may need to upgrade the starting rotation before the trade deadline. Who might he have in mind?

FOX Sports' Ken Rosenthal has the latest.

Apparently the Astros prefer to acquire a starter who will be a free agent after 2015. Those candidates include Jeff Samardzija of the Chicago White Sox, Scott Kazmir of the Oakland Athletics and Johnny Cueto of the Cincinnati Reds, among others. All have red flags regarding one aspect or another, but Houston needs to patch up their rotation and would like to do so without inheriting a long-term commitment.

"The Astros remain interested in White Sox right-hander Jeff Samardzija, among other available starters, according to major-league sources. And while the White Sox have not yet indicated a willingness to sell, that day could be coming soon," Rosenthal writes.

It's unknown how long White Sox general manager Rick Hahn is going to wait before shopping some of the team's veteran players, but it's likely he's considering it because the White Sox are the last-place team in the American League.

As for Kazmir, Athletics' general manager Billy Beane has not yet put up the for-sale sign in Oakland. Previous rumors suggested Beane is not giving up on the season this early and believes the team still has a chance. The club is still recovering from injuries, but has managed to win 12 of their last 15 games to make their situation more manageable. The A's (33-41) sit nine games behind the Astros and seven games behind the Minnesota Twins for the second wild-card spot.

If they can put together a few big runs before late July, Beane might be inclined to keep Kazmir and instead get draft pick compensation for the left-hander in the offseason.

Same goes for Cincinnati, except trading Cueto remains a very likely scenario since the team won't be able to afford him after the season. Contenders will be lining up to discuss a deal for the right-hander (assuming teams are comfortable with his recent elbow inflammation) and the Reds will be able to get a good return.

Earlier rumors linked Cueto to Houston, so it's definitely a possibility.

However, Evan Drellich of the Houston Chronicle said a few days ago the Astros may not be quick to jump the gun on making such a trade just yet.

"The Astros are in need of starting pitching help in the majors and would love nothing more than to have [Mark] Appel step in and aid the team," Drellich wrote. "Lance McCullers Jr. has been more consistent (and also had more time in the bigs) than Vincent Velasquez, both pitchers who came straight from Class AA to the majors. The Astros want to assess what they have in-house before making a move for an outside pitcher potentially."

Luhnow cleared the air on that yesterday.

"I don't think [Appel's] going to be here in a time frame that changes what we're going to do as far as adding to this team for a playoff stretch," Luhnow told Drellich.

Keep an eye out for the Astros to chase impending free-agent pitchers before the deadline.