Brazilians furious at corruption demonstrated Sunday in support of a politically explosive probe into high-level embezzlement and bribery, but turnout was significantly lower than at previous protests. The long-planned day of nationwide demonstrations kicked off in the capital Brasilia and Rio de Janeiro, before shifting to the nation's biggest city Sao Paulo. Protesters, many wearing the yellow shirts of the country's beloved football team or draping themselves in the Brazilian flag, said a huge investigation known as Operation Car Wash must not let up in intensity. "We're supporting Car Wash. It's an operation that must go all the way," said Teresa Kohler, 51, who was in Rio helping to organize the demonstration with the group Take to the Streets. "We must punish the corrupt, make a real cleanup and build a new Brazil." With the number of politicians targeted by the probe rapidly increasing -- reportedly now including around half a dozen members of President Michel Temer's cabinet -- many in Brasilia are trying to slow Car Wash down. Protesters focused their anger on a law putting all criminal cases involving politicians in the hands of the Supreme Court, which moves at a snail's pace, taking years to bring prosecutions to trial. "The worst are the Congress members," said Elisangela Colombo, 43, at the Sao Paulo protest. "I came to demonstrate against them because they keep passing laws in their own interest. They're afraid and want to stop Car Wash." Compared to similar demonstrations over the last two years, Sunday's event was notably smaller. Just hundreds gathered in Brasilia and only several thousand in Rio on the iconic Copacabana beachfront. The Sao Paulo turnout was also far off the huge crowds that gathered over the last two years to call for the impeachment of leftist president Dilma Rousseff, who was eventually ejected last year and replaced by center right Temer. Cintia Gante, a 51-year-old real estate agent in Sao Paulo, said the seemingly endless revelations of corruption no longer had "novelty." "People are getting tired," she said. Rogerio Chequer, head of Take to the Streets, told reporters in Sao Paulo that the protests were still significant. "The number is not our main focus today, it's the message we're sending," he said. "If at the end of the day Brazil understands what's happening in Brasilia, then our objective has been met." - Desperate measures? - Operation Car Wash has uncovered a vast web of politicians and executives who fleeced state oil company Petrobras, with a lot of dirty money funneling into party election funds. The probe got even bigger this month with a request by Prosecutor General Rodrigo Janot to open new investigations expected to target more than 100 politicians. A week ago, Brazilians got a shock on a new front when police said they'd uncovered a scheme to bribe corrupt health inspectors at meatpacking plants to certify tainted meat. The revelation prompted several big markets, including China, to impose brief but damaging import bans. As Car Wash's crusading chief judge Sergio Moro advances, a panicky Congress is trying to push back. Lawmakers have attempted to pass legislation that would pardon anyone who had received undeclared campaign donations in the past, while making it illegal in the future. This would effectively become an amnesty for politicians who took secret donations or what may have been plain bribes. Another initiative being discussed is to change the electoral system so that voters cast ballots for parties, not individual candidates, meaning that scandal-tainted politicians would be able to escape much of voters' direct anger. The result is an ever-widening divide between politicians and voters. Protester Paulo Rachid, 63, an engineer in Rio, described Temer's ruling PMDB party as a machine existing only to make money for its members. Corrupt politicians are "a gang that has taken control of Brazil. They have infiltrated at every level of society," he said. Among fed-up Brazilians, Moro is seen as a hero -- one of the only figures left in public life who is on the right side. "He should be president," said Rio street vendor Edison Reis, 60, brandishing an inflatable Moro doll that he was selling for 20 reais ($6.45). "And all the rest should be put in prison."