BRASILIA, Nov 9 (Reuters) - Brazil"s lower house of Congress approved a constitutional amendment on Tuesday that would allow far-right President Jair Bolsonaro to spend an additional 92 billion reais ($16.5 billion) next year to ramp up welfare spending ahead of elections. The chamber voted 323-172 in a second vote required for changes to the constitution and the measure now advances to the Senate, where Bolsonaro has said it may face resistance. The amendment would spread out the government"s court-ordered payments of certain debts and judicial settlements, allowing it to spend more on social welfare programs. It has rattled financial markets worried that increased spending will deepen Brazil"s budget deficit. Bolsonaro pressed lawmakers earlier on Tuesday to back the amendment, saying in a local media interview that if the government was forced to pay all the court-ordered obligations coming due next year, it "would bankrupt Brazil." His opponents, said, however, the bill was aimed at circumventing a constitutional spending cap so that the government could double social welfare programs in a populist drive to win votes in next year"s presidential election. The amendment is crucial for the government to be able to fund a revamped welfare program to be called Auxilio Brasil that will replace the long-standing Bolsa Familia program begun by leftist former President Luiz Inacio Lula da Silva. Bolsonaro"s plan is to double monthly stipends to 400 reais ($73) and expand the program to cover 17 million poor families. "Bolsa Familia lasted 18 years and never needed a change to the constitution to be funded. This is aimed at buying votes in next year"s elections," said Bira do Pindare, a congressman for the Brazilian Socialist Party (PSB). He said the government had used a "secret budget" of pork-barrel earmarks to encourage lawmakers to pass the measure. Bolsonaro is expected to face Lula in the election next October, although neither has officially declared his candidacy. Opinion polls show seven in 10 Brazilians would pick one or the other as their first choice for president, with surveys showing Lula with a comfortable lead at the moment. ($1 = 5.5103 reais) Reporting by Maria Carolina Marcello and Ricardo Brito; Writing by Anthony Boadle and Gabriel Stargardter; Editing by Peter Cooney