Jerusalem Talmud Yevamot 4:5

משנה: מִצְוָה בַּגָּדוֹל לְיַיבֵּם לֹא רָצָה מְהַלְּכִין עַל כָּל הָאַחִין. לֹא רָצוּ חוֹזְרִין אֵצֶל הַגָּדוֹל וְאוֹמְרִים לוֹ עָלֶיךָ מִצְוָה אוֹ חֲלֹץ אוֹ יַבֵּם. MISHNAH: The obligation of levirate is on the oldest [brother]¹⁰³Already stated in Mishnah 2:8.. If he refuses, one¹⁰⁴The local rabbinic court whose obligation it is to enforce the rules; cf. Maimonides, Hilkhot Yibum 2:7. goes to all the other brothers. If they refuse, one returns to the oldest and tells him, the obligation is yours, either give ḥalîṣah or marry in levirate.