Merkel, a conservative, was seeking to end her "grand coalition" with the center-left Social Democrats of challenger Frank-Walter Steinmeier and form a government with the pro-business Free Democrats instead.

Both ARD and ZDF television forecast that she was on track to do so _ helped by a very strong showing for the Free Democrats.

An ARD television exit poll put support for Merkel's Christian Democrats at 33.5 percent of the vote and for the Social Democrats at 22.5. It had the Free Democrats at 15 percent, the Left Party at 12.5 percent and the Greens at 10.5 percent.

A ZDF exit poll put the conservatives on 33.5 percent and the Social Democrats on 23.5 percent. It gave the Free Democrats 14.5 percent, the Left Party 13 percent and the Greens 10 percent.

If the results are borne out, it would be the worst parliamentary election result for the Social Democrats since World War II.

Merkel argued that a change of coalition was needed to ensure stronger economic growth. In joining with the Free Democrats, she hopes to cut taxes and halt a plan to shut down Germany's nuclear power plants by 2021.

Volker Kauder, the conservatives' parliamentary leader, said a center-right majority appeared "reachable."

"We have achieved our election aims and it is a good result for our country," Kauder told ARD.

"We have suffered a bitter defeat," said his Social Democratic counterpart, Peter Struck.