The California Legislature is signaling that it could cancel a $400 million loan payment to help finance a longer lifespan for the state’s last nuclear power plant. The votes in the state Senate and Assembly exposed a rift with Democratic Gov. Gavin Newsom, who says a longer run for the Diablo Canyon plant is critical to maintaining reliable power supplies. The dispute is part of continuing negotiations over a new state budget. The state has endorsed a five-year extension for the plant beyond a planned closing by 2025. Legislators want more information on repayment of state loans by operator Pacific Gas & Electric.