The bill was expected to be ready when lawmakers returned next week.
Boxer is the chairwoman of the Senate Environment and Public Works Committee, the panel that has primary jurisdiction over the bill.
Kerry has been a longtime proponent of capping carbon dioxide. He has used his gavel as the chairman of the Senate Foreign Relations Committee to examine how rising global temperatures could destabilize certain regions.
Sen. Reid (D-Nev.) had asked the committees with oversight on climate-related issues to have bills ready by the end of September. The delay announced by Boxer and Kerry could make it more difficult for Reid and other Democratic leaders to work out a compromise bill that can muster the 60 votes needed to proceed in the Senate by the end of the year.
“They are working diligently to craft a well-balanced bill and Senator Reid fully expects the Senate to have ample time to consider this comprehensive clean energy and climate legislation before the end of the year,” Reid spokesman Jim Manley said in a statement Monday.