NEW YORK — Mired in a weeks-long slump, the New York Mets are moving struggling starting pitcher Frankie Montas to the bullpen, paving the way for one of their top pitching prospects for a major-league debut on Saturday.

Both Nolan McLean and Brandon Sproat have pitched well at Triple-A Syracuse, setting them up as leading candidates to replace Montas. McLean has been the more consistent pitcher over the course of the season, and Saturday would be his normal day to pitch.

Neither Paul Blackburn nor Tylor Megill, both on rehab assignments in the minors, would be ready in time for that start.

It’s been a difficult season for Montas, who signed a two-year, $34 million contract with the Mets last winter. He suffered a right lat strain in spring training and missed the first three months of the season. He was hit hard even in his rehab assignment, and he has labored to put together good starts at the major-league level. In Montas’ last game on Saturday, the Mets used an opener ahead of him, and he recorded just nine outs in what became New York’s sixth consecutive loss.

Montas owns a 6.38 ERA in eight games (seven starts) this season.

“We need to see consistency,” manager Carlos Mendoza said. “It’s been a battle for him. He understands where we’re at in the season.”

The Mets’ third-round pick in 2023, McLean, originally a two-way player, has taken off as a pitcher since he ditched hitting last summer. Since being promoted to Triple A in early May, McLean has posted a 2.78 ERA and held opponents under a .200 average and .300 slugging percentage. He’s permitted more than two runs twice in 16 Triple-A starts.

Sproat entered the season as New York’s top pitching prospect — someone likely to be on call in case of an injury early in the year. The Mets’ initial starting depth held, and Sproat struggled to begin the season with Syracuse, enough for Blade Tidwell to get the call ahead of him back in May.

Sproat, however, has been on a heater since his final start in June. Over his last seven outings, he’s allowed just five earned runs across 39 innings while striking out nearly 30 percent of opposing hitters.

While McLean would be on normal five days’ rest for Saturday, Sproat’s last outing was on Thursday. He’d need to either sit for an extended period or see abbreviated action early this week ahead of a big-league debut Saturday.

The Mets’ starting staff had been the strength of the team through the season’s first two and a half months; in mid-June, it led the majors in ERA by a considerable margin. But over the last two months, the rotation has dragged the Mets down. New York is 25th in rotation ERA in that span, and no starter outside of David Peterson has finished even the sixth inning over those two months.

Losers of seven straight, 11 of 12 and 31 of 49 entering Tuesday, the Mets are hopeful that either McLean or Sproat can provide them with the kind of boost of energy brought last May by Mark Vientos and José Iglesias, or late last season by Luisangel Acuña.

(Photo: Orlando Ramirez / Getty Images)