Voting began Sunday in Poland’s presidential runoff election, with nearly 29 million registered voters choosing between liberal Warsaw Mayor Rafal Trzaskowski and conservative nationalist Karol Nawrocki in what has become quite a tight race.

Polls opened at 7 am local time and will close at 9 pm, according to the country's National Electoral Commission.

The runoff was triggered after neither candidate secured more than 50 percent in the first round on May 18, which saw a turnout of 67.31 percent.

Trzaskowski, 53, narrowly led the first round with 31.36 percent of the vote, followed closely by Nawrocki, 42, who garnered 29.54 percent of support.

The outcome of this election is expected to have significant implications for Poland's political direction and its relationship with the European Union.