Slay and Harrison skipped mandatory minicamp in June to voice their displeasure with their current deals. Both lost workout bonuses of $250,000 and were fined $88,650.
Birkett says it’s unclear if either player will report to the start of Lions training camp on July 24 without a new deal. The fines for missing camp would be $40,000 per day.
The pair are represented by Drew Rosenhaus.
Slay, 28, is a former second-round pick of the Lions back in 2013. He played out his rookie contract before agreeing to a four-year, $50.2 million extension that included $23 million fully guaranteed.
Slay stands to make a base salary of $12 million for the 2019 season.
In 2018, Slay appeared in 15 games for the Lions and recorded 43 tackles, three interceptions, one defensive touchdown, and 17 pass defenses.
Harrison, 30, originally signed on with the Jets as an undrafted free agent out of William Penn back in 2012. He spent four years with the Jets before departing in free agency for a five-year, $46.25 million contract that included $24 million guaranteed with the Giants.
The Giants later traded Harrison to the Lions in return for a 2018 fifth-round pick. Harrison stands to make base salaries of $6.75 million and $9 million over the next two years.
In 2018, Harrison appeared in 10 games for the Lions, recording 50 total tackles, 3.5 sacks, one forced fumble and one fumble recovery. In seven games for the Giants, he recorded 31 tackles, no sacks and a forced fumble.