WASHINGTON — Both sides in the NFL’s labor talks are trying to spread the word by putting their positions in writing, and everyone’s getting in on the act — from Hall of Fame players Jack Youngblood and Bruce Smith, to Commissioner Roger Goodell, to mayors of league cities.

In a letter obtained by The Associated Press on Tuesday, Youngblood and Smith asked NFL owners to promise not to lock out players even if a new collective bargaining agreement isn’t reached by the time the current one expires at the end of the day March 3.

Youngblood was elected to the Pro Football Hall of Fame in 2001, Smith in 2009. Their letter was addressed to “Owners of the National Football League” and sent Jan. 31 to Goodell at league headquarters in New York.

“As former players, it is crystal clear that the vast popularity and financial success of football means that a lock out cannot be in the interest of anybody involved, particularly the fans who support the game,” Youngblood and Smith wrote.

They noted that the players’ union already “pledged to not strike.”

“By making the parallel commitment,” they wrote, “the owners would create the breathing room for a deal to be struck.”

That exact wording also was used in a Feb. 7 letter from Kansas City, Mo., Mayor Mark Funkhouser to Clark Hunt, the owner and chief executive officer of that city’s NFL team, the Chiefs. .

Mayors or city officials from at least five sites of NFL teams have written letters to the league or a club official to argue against a lockout.

Goodell, meanwhile, indicated in an oped piece that the 2011 regular season could be in jeopardy if the league and union don’t start “serious negotiations” toward a new CBA soon.

He said he “cannot emphasize enough the importance of reaching agreement by” the expiration of the old CBA.