SAO PAULO, Aug 23 (Reuters) - The governor of Brazil"s Sao Paulo state on Monday fired a senior military police commander who publicly supported a march in favor of President Jair Bolsonaro and attacked rival politicians. The firing of Aleksander Lacerda, who led a regional Sao Paulo force with some 5,000 men under his command, highlights the widespread support Bolsonaro, a far-right former army captain, has among Brazil"s roughly 500,000 military police. Critics say Bolsonaro is seeking to marshal their support ahead of a highly contentious presidential election next year. Bolsonaro, who trails former leftist President Luis Inacio Lula da Silva in most polls, has cast doubts on the electoral process and attacked election authorities, sparking fears he may not accept a loss. If the country"s military police were to support his claims, it would pose major democratic risks in Latin America"s biggest country, experts say. Active-duty military police are prohibited from making political demonstrations. According to the Estado de S. Paulo newspaper, Lacerda posted on Facebook asking "friends" of the president to attend a Sept. 7 march in support of Bolsonaro. "Freedom is not gained, it is taken," he wrote, according to the newspaper report. "On 7/9, I will go." He also criticized his ultimate boss, Sao Paulo Governor Joao Doria, and attacked senior lawmakers as "cowards" and "mafiosos." Doria, while praising the state"s military police, announced Lacerda"s firing at a press conference on Monday. The officer "was removed this morning from his duties in the military police for indiscipline," Doria said. "Here in Sao Paulo state, we will not have political demonstrations by active duty military police officers." The state military police said in a statement that Lacerda"s case will be analyzed by its internal affairs department.