Ted Cruz, Bernie Sanders peg back Donald Trump, Hillary Clinton

Republican presidential candidate Donald Trump signs the arm of a girl at the CFE Arena on the campus of the University of Central Florida in Orlando on Saturday. — AFP

Senators Ted Cruz and Bernie Sanders scored key victories in the 2016 quest for the White House, but Donald Trump and Hillary Clinton remained their parties’ frontrunners as the “Super Saturday” results came in.

Republican Trump and Democrat Clinton both won in the delegate-rich state of Louisiana, keeping them on top at a critical point in the US presidential race.

Results from votes in five states were split, but one element was clear: Republican Cruz boosted his claim as the most viable alternative to billionaire Mr Trump after taking Kansas and Maine, and put poorly performing Senator Marco Rubio under pressure to turn his campaign around or bow out.

And Mr Sanders’ victories showed that the self-described Democratic Socialist can stay in the race despite the long odds of defeating Ms Clinton.

Mr Cruz and Mr Sanders can also claim momentum as they head toward critical races in Michigan next Tuesday, and then winner-take-all races in the large states of Florida and Ohio on March 15.

“Thank you to Louisiana, and thank you to Kentucky,” Mr Trump said in Florida, minutes after he won in Kentucky, where he led Mr Cruz by four percentage points.

The races were the first test of whether the Republican establishment’s desperate effort led by 2012 nominee Mitt Romney to halt Mr Trump is having any effect. Mr Trump declared those efforts a failure, and called on Mr Rubio, once seen as the best hope to defeat him, to quit.

“Marco Rubio had a very, very bad night. Personally I’d call for him to drop out of the race,” Mr Trump said.

“I would love to be able to take on Ted one on one,” he added.

“That will be easy.”

Mr Trump is well ahead in the all-important delegate count for Republicans, having now won 12 of the 19 states that have voted up to now.

But the strong showing by Mr Cruz — who won more delegates than Mr Trump on Saturday — indicates that the brash real estate mogul is not the inevitable nominee.

Arch-conservative Texas Senator Cruz performed beyond expectations in Kansas, where he earned 48.2 per cent support, more than twice as Mr Trump, who received 23.3 per cent.

Third was Mr Rubio at 16.7, followed by Ohio governor John Kasich, who with a string of disappointing results must also consider his position.

It was a startling 13-point win for Mr Cruz in the more moderate New England region of Maine.

Mr Cruz exulted in his victories during a campaign rally in Idaho, which did not vote on Saturday.

“The scream you hear — the howl that comes from Washington DC — is utter terror at what we the people are doing together,” he said, adding that conservatives are “coming together... And standing as one behind this campaign.”

The Republican race is down to four men: political outsiders Mr Trump and Mr Cruz, and more mainstream candidates Mr Rubio and Mr Kasich. Many in the Republican establishment are apoplectic over Mr Trump’s frontrunner status and would like to back a single opponent.

Mr Cruz claims to be that man, and called on Mr Rubio and Mr Kasich to drop out. “The field needs to continue to narrow,” Mr Cruz told reporters late Saturday.

“If we’re divided, Donald wins,” he warned.

Among Democrats, Mr Sanders savoured victories in Kansas and Nebraska, pushing his total to seven victories from 18 contests.

“We’ve got the momentum, the energy and the excitement that will take us all the way to the Democratic National Convention in Philadelphia,” Mr Sanders said in a statement.

But Ms Clinton decisively swept Louisiana, the weekend’s big prize, with 59 Democratic delegates at stake compared to 37 for Kansas and 25 for Nebraska.

The former secretary of state dominated in Louisiana, a state with a substantial African-American vote.

Mr Sanders did well in the other two states in part because of their large white populations, a demographic with which he does well.

Maine, also overwhelmingly white, holds its Democratic caucus Sunday.