MANILA - Unlike in the United States, the Philippines' vice-president is elected separately from the president. But like in the US, candidates for president and vice-president usually belong to the same party or coalition.
So, they campaign together.
But that does not guarantee a win for both. In fact, since 1986, when the office of the vice-president was restored after the late strongman Ferdinand Marcos abolished it in 1972, the elected vice-president has either been an independent or belonged to a party different from the elected president's.
Under the Constitution, the vice-president is a ceremonial head. He inherits the highest office, in case something happens to the president.
But some vice-presidents have used their political clout to negotiate with the president a post that gives them a platform to pursue their ambitions.
Former president Fidel Ramos created the position of "anti-crime czar" for his vice-president, the movie actor Joseph Estrada.
When he became president, Mr Estrada gave the social welfare portfolio to his vice-president Gloria Arroyo, who also went on to become president.
Current Vice-President Jejomar Binay, who is now running for president, was named "housing czar" by President Benigno Aquino.
This year's race for vice-president is interesting because Marcos' son, Senator Ferdinand Marcos Jr, is a lead contender. If he wins, that will mark a spectacular return for the Marcoses after their humiliating exile back in 1986.
But he has a steep hill to climb.
In the latest and last survey by polling firm Pulse Asia before Monday's (May 9) elections, Mr Marcos fell behind Ms Leni Robredo, widow of a popular government minister and vice-presidential candidate of Mr Aquino's ruling party. He now trails her by two points, in a race that analysts say promises a more dramatic finish than the presidential race.
Three other candidates are in the running, all senators: Mr Francis Escudero, Mr Alan Peter Cayetano, and Mr Gregorio Honasan.
Here is a look at the top 3 candidates for vice-president:
SENATOR FERDINAND MARCOS JR
He is the vice-presidential candidate for Senator Miriam Santiago, who is running for president.
Namesake of the late dictator but known more as "Bongbong", Mr Marcos is on the verge of completing a remarkable political comeback for a family that 30 years earlier had been vilified as plunderers of the nation's wealth.
He is riding on sentiments among a huge bloc of voters born after 1986 who see the Marcos years as a period of promise, and consider the 1986 People Power revolt - that installed democracy icon Cory Aquino and four other presidents - a failure.
With his father's old bailiwick - a voting bloc of 9 million in the northern Philippine region of Ilocos - behind him, Mr Marcos won a seat in the House of Representatives in 1991.
He then set off on a three-term stint as governor of Ilocos Norte from 1998 to 2007.
His service as governor was marked by a sense of renewal in Ilocos. He transformed Ilocos Norte from a sleepy, tobacco-dependent agricultural province into a bustling commercial hub, and stewarded the nation's biggest wind energy project.
He returned to the House of Representatives in 2007, and stayed there till 2010.
In 2010, he won a seat in the Senate, placing seventh with over 13 million votes behind him.
He is married to Ms Louise Araneta, now 57, a lawyer and scion of one of the Philippines' wealthiest clans. The couple have three sons: Sandro, 22, Simon, 21, and Vincent, 19.
REPRESENTATIVE LENI ROBREDO
She is the vice presidential candidate for former interior minister Manuel Roxas, who is running for president.
Through most of her married life, Ms Robredo had been carving her own quiet career as lawyer, economist, social activist and supportive wife to a rising political star. But her husband's untimely death in a plane crash in 2012 drew public attention to her.
Her husband, former interior minister Jesse Robredo, had been a long-serving mayor and distinguished public servant. After his death, Mr Aquino decreed Aug 18 as "Jesse Robredo Day", a special, non-working holiday.
On the strength of her husband's reputation, Ms Robredo was elected to Congress in May 2013, defeating the patriarch of a powerful political clan.
She has since been cultivating the same reputation for frugality and simplicity as her husband's. She still takes the eight-hour bus ride from Manila to Naga, and eschews red-carpet events.
Analysts say Ms Robredo appeals to liberals and good government advocates, and her rise has been powered by anti-Marcos forces who dread the prospect of seeing another Marcos within a step away from becoming president.
She has three daughters.
SENATOR FRANCIS ESCUDERO
He is the vice-presidential candidate for Senator Grace Poe, who is running for president.
An early favourite, Mr Escudero had fallen to No. 3 in surveys.
Mr Escudero is a scion of a well-connected political family. His father was agriculture minister under the Marcos regime.
A lawyer, Mr Escudero was a member of the House of Representatives from 1998 to 2007.
As congressman, he was among those who pushed for the impeachment of then President Gloria Arroyo on charges of electoral fraud. He also blocked efforts to amend the Constitution.
He won a Senate seat in 2007, and had been a senator prior to his bid to become vice-president.
Mr Escudero had supported Mr Aquino's presidential run in 2010. The two, bonded by their love for cars and smoking, had been congressmen and senators at about the same time.
Mr Escudero has been mocked for his monotonous speaking style that many had found so "robotic" that it had been likened to the voice on the traffic-navigation app Waze. In his defence, he said he settled on it as a "defence mechanism" when, as a young lawmaker, he was not taken seriously. The "robotic" voice was supposed to make him sound serious, he said.
Mr Escudero is married to an actress, and has two children by a previous marriage to a lounge singer.