FACTBOX - Main candidates in Serbia's presidential election

(Reuters) - Serbs vote on Sunday in a presidential election, with opinion polls giving hardline challenger Tomislav Nikolic a slim lead over pro-Western incumbent Boris Tadic, but not enough for a first-round victory.

Here are profiles of the main candidates:

TOMISLAV NIKOLIC (Radical Party)

Orientation: nationalist, eurosceptic

Promises: keep Kosovo within Serbia but without going to war; fight crime, corruption; promote employment and people-friendly economic growth strategies.

Quote: "If I win these elections, it is Serbia that will win, not Moscow, not Brussels, not Washington."

Slogan: "With all our heart"

Recent poll figures: around 33 percent

BORIS TADIC (Democratic Party)

Orientation: centrist, pro-Western

Promises: keeping Kosovo within Serbia but also moving towards the European Union; jobs, health care, education; fight against corruption.

Quote: "The future of Serbia is in Europe, but Serbia needs to preserve its identity. I will never give up Kosovo nor our identity."

Slogan: "For a strong and stable Serbia"

Recent poll figures: around 30 percent

VELIMIR ILIC (New Serbia/Democratic Party of Serbia)

Orientation: populist

Promises: development and infrastructure to improve living conditions; employment; keeping Kosovo within Serbia.

Quote: "The low birth rate is a huge problem and we have to adopt laws to change it. The new president has to get involved in solving this problem."

Slogan: "From the people, for the people"

Recent poll figures: around 6 percent

CEDOMIR JOVANOVIC (Liberal Democratic Party)

Orientation: liberal, pro-Western

Promises: rejecting the nationalist values of the war-torn 1990s, joining Europe; emphasis on youth, fast reforms.

Quote: "The Kosovo problem is being misused in order for Serbia to get off the European path."

Slogan: "Life rules"

Recent poll figures: around 6 percent

MILUTIN MRKONJIC (Socialist Party)

Orientation: Populist, nationalist

Promises: social justice, nationalizations, higher pensions.

Quote: "Slobodan Milosevic is a charismatic historic personality, I would never be able to reach his level. Nobody can copy him such an honorable, honest, special man."

Slogan: "Our comrade"

Recent poll figures: around 6 percent

(Writing by Ellie Tzortzi; Editing by Keith Weir)