In the last elections in 2009, there was a 70 percent voter turnout, an all-time low in Germany, euronews.com reported.
Germans are voting for the chancellor position as well as seats in parliament.
An average of polls indicate Merkel's Christian Democrats and Christian Social Union of Bavaria coalition are likely to receive 38.6 percent of the votes, the Social Democrats 25.8 percent, and the Free Democratic Party 6.4 percent, London's Electionista predicted.
Despite those numbers, Social Democrat leader Peer Steinbruek urged his supporters to believe in the possibility of winning a majority of votes, the BBC reported.
"The voters decide," he said, "not commentary beforehand."
"It's not a game. Don't believe it's decided yet -- it isn't. I would ask for the voters' decision to be respected, because it's them, not political polls or certain observers, who decide an election," he added.
An estimated 30 percent of people are expected to decide who they'll vote for at the last minute, euronews.com reported.
Sign language interpreter at Mandela service called out as fake on Twitter
N.J. man wakes up from 10-hour sleep with knife in back