Washington, US (BBN)-Republican presidential candidate Ted Cruz has decisively won the Wisconsin primary, complicating front-runner Donald Trump’s path to the nomination.
In the Democratic race, Bernie Sanders scored a strong victory over Hillary Clinton in the Midwestern state, reports BBC.
Mr Trump leads the Republican race, but there are concerns that he could fall short of the number of delegates needed to secure the party’s nomination.
Mr Trump’s rivals have pinned their hopes on a contested convention.
At a contested convention, party leaders, not voters, would choose the nominee.
Mr Trump said on Tuesday he would prevail despite the loss and took aim at his rival.
“Ted Cruz is worse than a puppet – he is a Trojan horse, being used by the party bosses attempting to steal the nomination,” the Trump campaign said in a statement.
Party leaders are concerned that Mr Trump would be a weak candidate in the general election and could harm other Republicans lawmakers on the ballot.
Polls show that the real estate tycoon is extremely unpopular among key voting blocs including women, Latinos and young people.
On the Democratic side, Wisconsin adds to a recent spate of wins by the Sanders campaign, giving the Vermont senator a boost before key races in New York and Pennsylvania.
Mr Sanders won nearly every county in the state except Milwaukee, but as delegates are awarded proportionally he will not gain a significant advantage over Mrs Clinton.
Of the 86 Wisconsin delegates, Mr Sanders is on course for at least 44, but Mrs Clinton will have at least 28.
Addressing supporters in Wyoming, which holds its primary on Saturday, Mr Sanders stressed momentum was on his side and that his outsider candidacy could change the status quo.
“Real change never takes place from the top down; it always takes place from the bottom up,” Mr Sanders told supporters.
Mrs Clinton still holds a sizeable lead and most analysts say she will eventually become the Democratic nominee despite her recent losses..
While Tuesday’s loss was a setback for Mr Trump, his campaign has time to rebound
The campaign now moves to large north-eastern states, where polls show Mr Trump holds significant leads.
Mr Trump’s loss in Wisconsin comes after a rocky week for the campaign, particularly with female voters.
The New York businessman repeatedly struggled to articulate his position on abortion. At one point, he called for women to be punished for having abortions, then quickly changed his mind.
His campaign manager Corey Lewandowski was also arrested, accused of manhandling a female journalist.

Mr Trump has vehemently defended Mr Lewandowski and rebuffed calls to fire him.
Meanwhile, outside groups opposed to Mr Trump’s nomination stepped up their efforts in Wisconsin, running negative television adverts.
Popular state leaders such as Governor Scott Walker and influential talk radio programme hosts also opposed the Trump campaign and threw their support behind Mr Cruz.