The very busy Day One of Republican White House hopefuls

Washington: The Iran deal, emission regulations and immigration orders frame Barack Obama`s legacy -- and they would all be toast on day one of a Republican presidency, vow conservative White House candidates.

Taken together, the Republican message seems to be: On inauguration day January 20, 2017, hundreds of key orders or accomplishments by the current president will be repealed.

Should he win election, Wisconsin Governor Scott Walker has pledged to "terminate" the Democratic administration`s hard-won Iran nuclear agreement "on my very first day."

Property tycoon Donald Trump, who currently leads the Republican field, said he would "immediately" rescind Obama`s executive orders on immigration and build a "great wall" to stem illegal flows of Mexicans into the United States.

Senator Rand Paul has pledged -- on day one -- to end the federal government`s "unconstitutional surveillance" of US citizens.

Former senator Rick Santorum stated he would immediately suspend all executive orders or regulations "that cost Americans jobs." 

And equally zealous conservative Senator Ted Cruz vowed to swiftly abrogate "every single unconstitutional or illegal executive action from Obama."

It would be a tall order to accomplish everything before midnight on inauguration day. 

And while Republican candidates speak of repealing and replacing the landmark health insurance reform known as Obamacare, they acknowledge doing so might take more time.

The rhetoric coincides with the historically high number of major candidates seeking the Republican nomination.

There are 17 in the race, 10 of whom will be on stage Thursday for the party`s debut debate of the 2016 cycle.

At least half of US voters have never heard of eight of them, according to a Quinnipiac poll. They are under pressure to out-do one another, and offering wildly ambitious pledges is one way to win attention.

Obama`s strategy to essentially bypass the Republican-controlled Congress, particularly on immigration and climate change, has fuelled conservative promises to roll back his actions.

"Everything that President Obama has done with a pen and phone can be undone on day one with a pen," Santorum, currently polling under two percent, said Monday.

There is a centuries-old tradition of promising the moon in American politics, and both parties are guilty.

"The first day you`re in office, my goodness you probably don`t even know where the pencils are kept," said political science professor Timothy Hagle at the University of Iowa.

"It`s more of a rhetorical flourish than anything else to suggest you`re going to do a huge number of things that first day, when you may not have your staff and cabinet in place."

Jeb Bush, the son and brother of two presidents and the Republican candidate most familiar with the White House, reminded rivals of how a commander in chief will need time getting up to speed before he or she changes the world.

"If you`re running for president, I think it`s important to be mature and thoughtful about this," he said in July.A presidency`s first 100 days have acquired a sense of myth and ideological grandeur, a gage of effectiveness of a new leader.

Franklin Roosevelt primed the New Deal in his first three months in office.

Conversely, John F. Kennedy downplayed expectations, saying "all this will not be finished in the first 100 days."

But the tendency to promise more than merely the possible is almost universal.

"Americans don`t want someone like Walter Mondale to say, in 1984, we have a long-term problem in our economy, it`s going to mean raising taxes," said American University professor and presidency expert Allan Lichtman.

"They want things done right away, and they want immediate benefits."

Unfulfilled promises litter the landscape: The middle class tax cuts Bill Clinton pledged in 1992 went up in smoke. George Bush urged Americans in 1988 to "read my lips: no new taxes" -- but two years later taxes rose.

And on his day one in 2009, Obama vowed to close the Guantanamo prison within a year. It remains open.

When promises aren`t enough, candidates resort to less subtle messaging.

Gun-rights advocate Cruz recently made "machine-gun bacon" by shooting a semi-automatic rifle with raw pork strips wrapped around the muzzle.

Paul shredded the tax code with a chainsaw.

If candidates are serious about day one action, however, they could take inspiration from Roosevelt.

Just hours after the Democrat`s 1933 inauguration, he had his entire 10-member cabinet sworn in, for the first time ever.