Argentina's centre-right governing coalition has won a sweeping victory in mid-term congressional elections.
The result will strengthen President Mauricio Macri's position as he seeks to complete his pro-market reforms.
He told supporters that they had shown it was possible to change the history of Argentina.
Former left-wing President Cristina Fernández de Kirchner secured a seat in the Senate, giving her immunity from corruption charges.
The vote was seen as a referendum on Mr Macri, who has worked to implement economic reforms he says are crucial to restore the country's economy.
His Cambiemos (Let's Change) movement won in 13 of Argentina's 23 provinces, including the five biggest population areas, official results showed. Despite the gains, he fell short of an overall majority in congress.
"We realised that many things can change, we realised that we could, we were encouraged by change, we overcame fear and resignation and reality accompanied us and is accompanying us," said Mr Macri, who is expected to run for re-election in 2019.
More than 33 million Argentines were eligible to take part in the vote, which saw a third of seats in the Senate contested, along with half of those in the lower house of congress.
Ms Fernández, who governed the country from 2007 to 2015, came in a distant second in the race in the province of Buenos Aires, the country's most populous.
Despite not coming first, she secured enough votes to make it into the Senate.
She thanked voters saying her party Citizen's Unity would remain a firm opposition to Mr Macri's economic agenda.
The ex-president, who faces corruption charges, still enjoys support among millions of low-income Argentines who benefited from her generous social spending. But critics say her populist policies damaged the economy.
She denies any wrongdoing saying the accusations are politically motivated.