The main political adviser to Brazil's far-right presidential candidate Jair Bolsonaro said he will work Monday to stitch together alliances with individual lawmakers to ensure a runoff victory for the former Army captain.
With the field reduced to two candidates, some analysts see Haddad as the natural inheritor of numerous centrist votes that will be up for grabs, but the scale of Bolsonaro's first-round success means that Haddad will have little room for manoeuvre.
Brazilian socialist presidential candidate Fernando Haddad talks to media after casting his ballot at a polling station in São Paulo, Brazil.
That made Bolsonaro the odds-on favorite in a runoff election later this month that could hurl Brazil into new political territory.
Congressman Onyx Lorenzoni said he was making good on Bolsonaro's campaign pledge to end a system of horse-trading between party leaders in Brazilian politics, blamed for endemic corruption as past leaders wielded vast patronage in exchange for legislative support.
"The choice in Brazil could not be more clear: a pro-America, pro-Israel, and pro-liberty conservative patriot, or a corrupt communist puppet who was placed in this election by Lula", Balaban added. The country shifted to the left in 2003 with the presidential victory of Luiz Inácio Lula da Silva - known as Lula - and his Workers' Party went on to govern for 13 years.
"What comes out from this election is a Congress more favorable to pass Bolsonaro's reforms", said Juliano Griebeler, political analyst at Barral M Jorge, a business consultancy.
But Haddad is facing a tough challenge, not least because he is running as a stand-in Lula.
In the most polarized election since the end of military rule in 1985, Bolsonaro is backed by a group of retired officers like Mourão who have criticized Workers Party governments and publicly advocate military intervention if corruption continues.
Bolsonaro, whose campaign was called "Brazil above all, God above everyone", has pushed a nostalgic narrative that he can bring back better times.
He is riding a wave of anger at the establishment after the uncovering of one of the world's largest political graft schemes, opposition to a return to power by the leftist Workers Party (PT) blamed for much of that corruption, and fears about spiking crime in the country with more murders than any other.
Bolsonaro's Social Liberal Party rose from relative obscurity to become the second biggest party in Brazil's lower house Chamber of Deputies, just four seats short of the well-established PT's 56 and far ahead of several traditional parties.
"He needs to say, 'Yes, we were culprits in this massive corruption scandal; we deeply, deeply regret what happened to Brazil, but we need to move on, ' " she said.
"We can't always vote for the same candidates, the same parties".