Voters in the US-state of Ohio on Tuesday rejected a measure that would make it harder to amend the state's constitution, including an upcoming referendum to guarantee abortion rights.

The proposal, known as Issue 1, would have lifted the threshold for passing future changes to the state constitution from 50% of voters to 60%.

It would also have made it harder for such changes to get on the ballot in the first place.

With more than 1.2 million votes counted, 60% of Ohioans had voted no to reject the proposal, compared with 40% who voted yes. The Associated Press has called the race.

Biden welcomes result as win for democracy

Although Issue 1 did not explicitly mention abortion, the proposal was considered a battleground for a separate measure to enshrine "a fundamental right to reproductive freedom" in the state constitution, which will be voted on in November.

"This measure was a blatant attempt to weaken voters' voices and further erode the freedom of women to make their own health care decisions," US President Joe Biden said in a statement on Tuesday night.

"Ohioans spoke loud and clear, and tonight democracy won."

Reproductive rights advocates now have their sights set on November's vote.

"Great news! Ohioans showed up to the polls and rejected the opposition's attempts to undermine democracy and restrict reproductive freedom," said Alexis McGill Johnson, head of reproductive health organization Planned Parenthood.

"Abortion is on the ballot this November. Mark your calendars now, Ohio!" she added.

In Ohio, around 59% of voters are in favor of legal abortions in most or all cases, according to an Associated Press poll from last year.

zc/jsi (AP, Reuters)