Commissioner Roger Goodell and NFL appear unlikely to secure union’s approval of moving back free agency in future years (Nam Y. Huh/The Associated Press)

INDIANAPOLIS — The NFL Players Association is unlikely to agree to a change to pro football’s calendar that would push back free agency by several weeks in future years, two people familiar with the union’s thinking on the issue said.

League officials are considering reworking the calendar to push back the NFL scouting combine, the opening of the free agent market and the draft by several weeks.

According to people familiar with the deliberations, the combine would be held in early March instead of late February. Free agency would begin in early April; this year the market opens March 12. The NFL draft would be held in early May instead of late April. Under that schedule, the sport would remain prominent and generate news for more of the year.

The changes would require the approval of both team owners and the union to be enacted, according to people with knowledge of the situation. But those familiar with the union’s thinking said the players are unlikely to agree to later free agency, in large part because players generally want to know as soon as possible where they’ll play the following season.

One person called the union’s approval of the proposed changes “not likely.”

Another said of later free agency: “That’s the part that strikes me as [having] no chance.” The union might be more agreeable, that person said, to changes in the scheduling of the scouting combine and the draft.

According to that person, the league previously has mentioned the possibility of changing  the sport’s calendar to give the NFL a major event in as many months as possible. But those talks came in the context of also adding a longer regular season that could result in the Super Bowl being played as late as Presidents’ Day weekend in future years, that person said.

League officials previously have proposed lengthening the regular season from 16 to 18 games per team. But the union has balked at a longer regular season and the league seems to have accepted that an 18-game season is unlikely to happen. Instead, the league now seems to be exploring the possibility of expanding the postseason field to add playoff games, while also reducing the preseason from four games to two.