WASHINGTON — Bryce Harper didn’t swing a bat for a second day in a row Sunday because of an infection left over from a blister on his left hand.

The Phillies remain optimistic that Harper won’t be sidelined for a long duration. But the reigning National League MVP also couldn’t guarantee that he will be ready to play Tuesday night in the opener of a two-game series in Texas.

“I don’t know yet,” Harper said. “It’s an infection, so whatever you think an infection would be, that’s where I’m at right now. It’s not good.”

Harper said the blister developed two or three weeks ago as a byproduct of taking swings in the batting cage. Although the blister, which was below his left index finger near his palm, has cleared up, the infection developed Saturday. Harper is taking antibiotics to treat it.

Asked if he tried to swing a bat Sunday, Harper said, “No way.”

“I’ve had many blisters on my hands and gotten through it, but I’ve never had an infection on my hand like this,” Harper said. “Just trying to wait that out and see how much better it gets.”

The injury disrupts a particularly hot streak during a torrid calendar year for Harper. He’s batting .404 (21-for-52), with five homers, a .492 on-base percentage, and a 750 slugging percentage in June. Beginning with the second half of last season, he’s hitting .332/.437/.668 with 49 doubles and 35 homers in 572 plate appearances.

Harper didn’t start the second game of Friday’s doubleheader, but interim manager Rob Thomson said it was a planned breather. The blister flared after Harper’s game-tying, pinch-hit double Friday night.

Without Harper, the Phillies mustered five hits in Saturday’s 10-inning, 2-1 victory and six hits in a 9-3 loss Sunday against Nationals rookie starter Jackson Tetrault. But they still managed to win four out of five games against the Nationals, who have the worst record in the NL.

“Of course you want to be undefeated and go 5-0,” Harper said. “But to get four out of five in a weekend like this, that’s huge.”

Thomson described Harper’s hand as “still swollen” Sunday, but said the training staff isn’t concerned that Harper’s absence may linger long into this week.

“I don’t think so,” Thomson said. “You never know, but I don’t think so. I just looked at it. I don’t have anything to compare it to other than what I saw [Saturday]. It looked a little bit better.”

Harper has been limited to being a designated hitter since the middle of April because of the elbow injury. He received a platelet-rich plasma injection last month in an attempt to speed the healing process. The Phillies were hopeful he may be cleared to try playing light catch before the end of June.

Camargo getting closer

Two weeks after straining his right knee, infielder Johan Camargo is on track to rejoin the Phillies, likely by Tuesday in Texas.

Camargo played a third game in a row Sunday at triple-A Lehigh Valley and continued to check boxes that would signal his return. He tested his knee by playing shortstop Saturday and has hit from both the left and right sides of the plate.

Kelly sent down

With Monday’s deadline looming to get down to 13 pitchers on the active roster, the Phillies optioned reliever Michael Kelly to triple A after Sunday’s game. Kelly made his major league debut Thursday night and pitched a scoreless eighth inning in a 10-1 victory over the Nationals.

Camargo is likely to take the roster spot vacated by Kelly.

Extra bases

Rookie infielder Bryson Stott snapped an 0-for-24 skid with an RBI single in the fourth inning. ... Kyle Schwarber extended his career-long on-base streak to 24 games with a single in the fifth inning. ... Nationals star Juan Soto went only 2-for-19 in the series, although he did hit a three-run homer Sunday. ... Infielder Nick Maton (sprained right shoulder) went to the Phillies’ complex in Clearwater, Fla., to continue his rehab. ... Entering play Sunday, center field prospect Johan Rojas was 31-for-31 in stolen-base attempts for high-A Clearwater. ... After a day off Monday, the Phillies will open a two-game series Tuesday night in Texas. Kyle Gibson (4-2, 4.04 ERA) will face his former team in the opener against Rangers left-hander Martín Pérez (4-2, 2.10).