If Labour wins the next general election, Sir Keir Starmer plans to give millions of EU citizens the right to vote.
According to manifesto promises, the Labour leader will grant voting rights to settled migrants and 16 and 17-year-olds.
The Conservatives, on the other hand, have accused Sir Keir of preparing the path for a new Brexit referendum and attempting to “rig” the outcome.
“Allowing foreigners to vote is Sir Keir Starmer’s admission that he doesn’t trust the British people,” a Tory spokeswoman said.
“He’s laying the groundwork for a referendum on rejoining the EU, which he campaigned so hard for, and now he wants to rig the outcome.”
Meanwhile, Cabinet minister Grant Shapps warned the Labour leader is seeking to “reopen” Brexit.
Mr Shapps told Sky News’s Sophy Ridge on Sunday programme: “What he’s actually doing to make that clear is reopening the Brexit settlement.
“This is a settlement we have made with EU countries to have reciprocal arrangements so British citizens abroad are able to vote in, for example, the local elections say in Spain and the same here. What he plans to do is actually reopen the Brexit settlement.
“So what else will he reopen, the Windsor Framework, the Cooperation Agreement with Europe?
“This again is Keir Starmer doing whatever he thinks is practical to do or at his personal advantage to do at that moment in time.
“He doesn’t have fundamental ideas he relies on. As I say he stood on one platform, he’s now shifting to a different platform. And he’ll do the same with reopening Brexit.”
According to The Telegraph, the measures will be included in Labour’s next manifesto.
Migrants who live continuously and pay taxes in the UK would be permitted to vote in general elections for the first time under the ideas.
The measure is intended to enfranchise approximately 3.4 million EU nationals with “settled status” in the United Kingdom.
Another 2.6 million people who have been awarded “pre-settled” status may be granted voting rights in the future.
Meanwhile, 1.4 million 16 and 17-year-olds, like those in Scotland and Wales, would be entitled to vote.