(Al Behrman / Associated Press)

Wilson Ramos suffered a slight setback during his rehab from a left hamstring strain, according to Manager Davey Johnson, and is “a long shot” to return for the all-star break next month. Ramos was running during first-to-third drills in Viera, Fla., and “slightly re-injured” himself two days ago, Johnson said.

“He’s had a rough couple years here,” Johnson said. “We love him and we need him back healthy.”

Ramos was about two weeks from completing his six-week rehab from the injury. He traveled to Viera last week. Before he departed Washington, Ramos said last week that he already was running, although not at full force, and was taking his second rehab from a hamstring strain slower than the first.

Ramos is a power-hitting catcher the Nationals could use but he has endured a string of injuries the past two years. He damaged his ACL and tore his meniscus in May 2012 and missed the rest of the season. He worked diligently on his rehab, and was behind the plate on opening day. He strained his hamstring April 13 and missed 14 games.

He came back but re-injured the hamstring May 15, pulling up when running out of the batter’s box on a double play in Los Angeles, and has missed 24 games while on the disabled list. Of the Nationals’s 64 games, Ramos has played in only 14.