The Washington Nationals are reportedly expressing interest in high-priced closer Jonathan Papelbon.

The first-place Nationals have engaged in trade discussions with the Philadelphia Phillies regarding Papelbon, according to Ken Rosenthal of FOX Sports, but apparently remain unwilling to absorb additional payroll mid-season.

Rosenthal says the Nationals would be open to a deal if the Phillies paid most of the pro-rated share remaining on the right-hander's $13 million salary this season.

Papelbon, whose contract includes a vesting option valued at $13 million for 2016, has limited no-trade protection to 17 teams and will block a trade if he's not promised a closing job, CSN Philly's Jim Salisbury reports. The Nationals already have a closer in right-hander Drew Storen, who's pitching to career-best success with a 1.73 ERA, 10.9 strikeout-per-nine rate, and 29 saves in 38 appearances this season.

Papelbon, meanwhile, is in the midst of yet another All-Star campaign. The 34-year-old veteran earned his 17th save of the season Friday and lowered his ERA to 1.59 in the Phillies' 5-3 win over the Chicago Cubs. He addressed the persistent trade rumors after the game.

"It's been public ever since they came out and said we were going to rebuild," said Papelbon, who will trigger his 2016 option if he finishes 14 more games this year. "They said that before the season even started.

"Just waiting for that to start happening. We've got how many days till it happens? We'll see."