U.S. Democratic presidential candidate Hillary Clinton lost the election but will likely win the popular vote, an outcome that has frustrated many of her supporters who believe it's time to scrap the electoral college political system.

Clinton is expected to win more votes than president-elect Donald Trump, once the final tally is completed. Several million ballots remained to be counted at the end of the week after Tuesday's election.

But she will become the fourth presidential candidate in American political history, and the second Democrat in recent times, to have garnered more actual votes than her opponent, and failed to secure the number of electoral college votes needed to win.

In the 2000 election, Al Gore won the popular vote but lost the election to George W. Bush. That hadn't happened since Grover Cleveland lost to Benjamin Harrison in 1888.

Critics of the system argue that these results, although atypical, are hardly fair or democratic.

Calls for electoral reform are not unique to the U.S. Canada is examining its political system, and Prime Minister Justin Trudeau has vowed to overhaul it.

The electoral college was a compromise between those who preferred a popular vote for president and those who, fearing that only candidates from bigger states would win, wanted Congress to determine who would prevail. (Halie Miller/Associated Press)

But there are those in the U.S. who see merit in preserving the electoral college.

"[Critics make] the assumption that the only legitimate form of selection is by majority vote," said Andrew Rudalevige, professor of government and legal studies at Bowdoin College in Maine.

"The United States is not a popular democracy; it's a representative democracy," he said.

"Democracy does not have to be solely by majority rule."

It was this issue that, in part, led to the formation of the electoral college when the U.S. Constitution was drafted, said Rudalevige. The electoral college was a compromise between those who preferred a popular vote for president and those who, fearing that only candidates from bigger states would win, wanted Congress to determine the outcome.

Every state has an allotted number of electors based on its size, for a total of 538. A presidential candidate who wins the majority of the vote in a state — with the exception of Maine and Nebraska — wins all the state's electoral votes.

Maine and Nebraska allocate two electoral votes to the popular vote winner, and then one each to the popular vote winner in each Congressional district (two in Maine, three in Nebraska).

The candidate who wins 270 electoral votes wins the presidency.

Constitutional amendment

Changing this system would require a constitutional amendment, which would be very difficult, says Joshua Tucker, professor of politics at New York University.

Changing the constitution requires one political party to be enormously powerful and control the process and three-quarters of the states, he said. Otherwise, there needs to be consensus across the parties that the constitution needs to be changed.

"If one party thinks they are advantaged by it, they're less likely to want to change it."

Gary Gregg, director of the University of Louisville's McConnell Center and a supporter of the electoral college, said the election wasn't a competition for the popular vote. That result may have been different, he said, had both candidates been competing only for the most votes.

Democrat Al Gore, left, won the popular vote in the 2000 election but Republican George W. Bush won more electoral votes, and therefore the presidency. (Ed Reinke/Associated Press)

If that was the case, he said, Clinton would not have gone to Arizona in the last week of the campaign digging for electoral college votes and Trump would have stayed away from Minnesota and Wisconsin. Instead, both candidates would have spent much of their resources in larger states.

The electoral college system, Gregg said, forces candidates of both sides to appeal across the spectrum of the American people, and not just sink the majority of their resources into the big states and big cities.

'Geography still does matter'

"There's something intuitive about the idea that you shouldn't be able to win the votes of just people in New York and California and win the presidency," added Rudalevige. "Geography still does matter, especially in a large geographic space like United States."

There has been a push by some for the National Popular Vote Interstate Compact, an agreement that would ensure that the electoral votes would go to whoever wins the popular vote. While this pact has been signed by 10 states and the District of Columbia, Rudalevige doubts the plan would be enforceable and believes it would face legal challenges.

"Do you really see voters in Oklahoma handing their votes to Clinton?" he said.

"It's not so much that the electoral college is magic, but it is known, and if you change the rules you will change the manner in which parties and candidates will compete under the rules.

"And I suspect you will have unintended consequences, that it comes down to what's the risk, what's the reward?"