With less than a week to go before Israel's general elections, two polls indicate that the center-left Zionist Union alliance, headed by Isaac Herzog, is leading the center-right Likud party, headed by Prime Minister Benjamin Netanyahu.

A Channel 2 TV poll published Tuesday said the Zionist Union would win 25 spots while Likud would win 21 spots in the 120-seat Knesset, which is Israel's Legislature. Similarly, a Knesset Channel poll said the Zionist Union would take 24 seats and the Likud party would take 21 in the elections scheduled for March 17.

Netanyahu said Tuesday that there was a "tremendous effort worldwide, to topple the Likud party," a week after he delivered a speech before the U.S. Congress about Iran's nuclear program. That appearance was condemned as interference in American domestic politics and criticized as a attempt to garner political support back home in advance of the elections.

One Israeli news site indicated that Netanyahu's speech to Congress had boosted the Likud party's chance of an electoral victory, but only temporarily. However, 49 percent of respondents in the Channel 2 poll said they wanted Netanyahu to serve as Israel's next prime minister, while 36 percent of respondents in the same poll said they wanted Herzog to serve as such.

As many as 14 percent of voters may be undecided, other reports suggested: Both the Zionist Union alliance and the Likud party are attempting to tap into that pool, while also trying to cull ballots from voters who are expected to support other political parties.

"The battle is very close," the New York Times quoted Netanyahu as saying Monday. "Nothing is guaranteed." His words were a far cry from the 2013 elections, when it was all but guaranteed that Netanyahu would be prime minister. The Zionist Union was established last year by Herzog, leader of Israel's Labor Party, and Tzipi Livni, leader of the Hatnuah party. If their alliance were to win, the two leaders would rotate the position of prime minister.

The Knesset Channel poll surveyed 1,027 Israeli adults -- twice as many as it usually does -- and its result have a margin of error of 3 percent. The Channel 2 TV poll's survey-pool size and margin of error were not specified in I24News' report on the results.