Nationals third baseman Ryan Zimmerman wants a new deal before the start of the season but many obstacles — including a no-trade protection — are holding up the contract extension. (Jonathan Newton/The WASHINGTON POST)

The Washington Nationals and third baseman Ryan Zimmerman must clear multiple major hurdles — most notably the issue of Zimmerman’s no-trade protection — before agreeing on a contract extension by the Saturday morning deadline Zimmerman has imposed, a person familiar with the situation said.

General Manager Mike Rizzo and Brodie Van Wagenen of CAA Sports, Zimmerman’s agent, met Thursday afternoon in Viera to discuss the extension. The face-to-face talks helped move the negotiations along, but did not necessarily nudge the sides any closer to a deal. The Nationals and Zimmerman’s camp have been in communication for more than a year, and the Nationals have known the amount of money it would take to sign Zimmerman to an extension since mid-January.

“We’re trying to reach the goal of getting him signed,” Rizzo said Thursday morning. “I don’t have a real good idea on the deadline, whether it’ll get done or not. We’re continuing to try.”

Thursday evening, Rizzo said he did not anticipate any updates to Zimmerman’s situation for the remainder of the night. Friday, then, could be a pivotal 24 hours for the direction of the Nationals, a day that could determine whether they will keep Zimmerman, 27, the face of their franchise since they made him their first ever draft pick in 2005, in Washington for the foreseeable future.

“We’re working extremely hard at it,” Rizzo said. “When both sides want something and they’re working at it, yeah, I’m hopeful. . . . We’ve got a player who wants to be in Washington, a GM and an ownership that wants him here. We’re working hard to get one of our franchise players signed here for the long-term.”

Zimmerman signed a five-year, $45 million deal on the eve of the 2009 season that runs through 2013, but baseball’s financial structure all but demands Zimmerman and the Nationals the reach an extension soon.

Zimmerman plans to test free agency if he does not receive a contract extension prior to the 2013 season. Without a deal now, the Nationals and Zimmerman would have to pick up talks in the winter, with the offseason becoming the sides’ only remaining negotiating window. Zimmerman playing this season without an extension also raises the possibility, however remote, of the Nationals considering trading the face of their franchise at the July 31 deadline.

Zimmerman has frequently made public his desire to finish his career in Washington, the only city where he has ever played, a short drive from his family in Virginia Beach. He entered into negotiations after a season in which he missed 60 games because of injury, willing to exchange market value for security. Naturally, then, he has insisted on a no-trade clause.

Under former team president Stan Kasten, the Nationals instituted a firm policy against no-trade clauses. But since Kasten’s departure, the Nationals have shown a willingness to offer no-trade protection. They signed outfielder Jayson Werth as a free agent to a seven-year, $126 million deal in December 2010 that included a full no-trade clause.

“We’ve opened that door,” Rizzo said at the winter meetings this December. “We prefer not to. It would be a huge part of the negotiation. For the right player and the right fit, I think you have to be open-minded and flexible to at least think about it and talk about it.”

Giving Zimmerman a full no-trade clause would not require an overwhelming commitment. Major league players with at least 10 years of overall service time and five seasons with the same team automatically receive full no-trade protection. Zimmerman has played six seasons with the Nationals, which means the Nationals could only trade him before the 2016 season, anyway.

Zimmerman first brought up the Saturday deadline in January, telling The Post it would not be fair to his teammates for his contract situation — how much money he makes, really — to become a constant clubhouse topic. The Nationals will hold their first full-squad workout Saturday morning, and Zimmerman does not want to distract from his play or his teammates.

Van Wagenen attended the Nationals’ workout Wednesday and remained in Viera though Thursday night, but was not present at the team’s complex for Thursday’s workouts. He did respond to requests for comment.

Rizzo said that Zimmerman’s deadline “won’t stop me from talking” to Van Wagenen regarding an extension during spring training. But Zimmerman has been adamant about not discussing his deal once baseball begins.

Zimmerman had a similar deadline, for opening day, before the 2009 season. While the team announced the deal well into the season, it had been agreed to, in principle, roughly 10 minutes before the season’s first pitch.

Zimmerman has also expressed an openness to be creative with a possible contract, whether that means deferred money or other kinds of unique structuring. He has also expressed confidence, based in part on a solid relationship with Rizzo, that a deal would be reached.

The next 24 hours will prove pivotal in determining whether or not he’s right.