The 2020 US election drew the highest turnout in more than a century, despite a raging pandemic and efforts by Donald Trump and his allies to undermine trust in the voting system.

It was declared the most secure election in US history. Yet states across America have spent months leveraging Trump's false claims of a stolen election to introduce restrictive laws that opponents say are an assault on voting rights.

The curbs have alarmed civil rights activists and prompted President Joe Biden to issue an 11th-hour plea Wednesday for the soul of the nation -- just as senators were voting against debating the issue.

"United States Senate needs to act to protect the sacred constitutional right to vote which is under unrelenting assault by proponents of the Big Lie and Republican governors, secretaries of state, attorneys-general, and state legislatures across the nation," he said in a statement.

"It is urgent. Democracy -- the very soul of America -- is at stake."

In Georgia, people handing out drinks or snacks to voters waiting in line can now be criminally charged. In Iowa and Kansas, people returning faulty ballots on behalf of voters with disabilities face prosecution.

Texas has banned drive-thru and 24-hour voting, as well as the promotion of mail-in voting by election officials. Similar laws in more than a dozen other states make life more difficult for voters, say activists.

"These state laws are often aimed at disadvantaging historically underrepresented communities, including communities of color, as well as lower-income voters and people with disabilities," the Center for American Progress said.

Sweeping reforms

More than 425 bills with provisions that restrict voting access have been introduced in 49 states in the 2021 legislative sessions, according to the liberal-leaning Brennon Center for Justice.

By the beginning of October, at least 19 states had signed off on 33 laws that restrict voting, the organization says.

Senate Democrats sought Wednesday to start debate on the Freedom to Vote Act, a sweeping package of voting, redistricting, and campaign finance reforms.

The legislation calls for automatic and same-day voter registration, two weeks of early voting and a new Election Day public holiday.

Crucially, it seeks to reduce the influence of money in politics, end partisan gerrymandering and fortify elections against foreign interference.

But it didn't garner the 60 votes needed to bring a debate to the floor, after Senate Minority Leader Mitch McConnell directed every Republican to reject the "latest iteration of Democratic efforts to take over how every American votes all over the country."

"Let there be no mistake," Democratic Senate Majority Leader Chuck Schumer said after the vote.

"Senate Republicans blocking debate today is an implicit endorsement of the horrid new voter suppression and election subversion laws, pushed in conservative states across the country."

Republican leaders in Congress argue that while the last election may not have been stolen, new laws such as photo identification requirements -- a normal measure in many countries -- are just common sense.

"The Democrats argue that (fraud) does not happen. Well, it doesn't happen very often because states do have things like photo ID, purging dead people from the rolls," McConnell said.

"These are normal administrative provisions that our Democratic friends would like to get rid of."

Trump's 'Big Lie'

Elections are administered locally in the United States, and Republicans tend to see Washington telling states how to run their own votes as federal overreach.

Yet Trump has been doing just that, for more than a year.

Starting before he was defeated by Joe Biden, and without a shred of evidence, the Republican firebrand has been engaged in a crusade to convince millions of Americans that the 2020 election was fraudulent.

Pressuring election officials in multiple states to invalidate results, Trump spread conspiracy theories in a bid to foment a seething fury over his election loss that culminated in the January 6 insurrection.

Biden was duly installed as the 46th president -- but Trump's so-called "Big Lie" ultimately worked.

Even after thousands of his supporters stormed the US Capitol, assaulting police and chanting death threats, 147 Republicans voted along the lines of the insurrectionists' objective to overturn the election in some states.

Meanwhile, a YouGov poll in August found that two-thirds of Republicans believe the last election was stolen from the twice-impeached Trump.

Top Democrats including national committee chief Jaime Harrison, Senate Judiciary Committee chairman Dick Durbin and House Leader Steny Hoyer reacted with anger to the blocked Senate debate on the Freedom to Vote Act.

"Republicans have made it abundantly clear that they are willing to prioritize political games and power over our fundamental rights," said Harrison.

"They've chosen to serve the Big Lie over the American people."