Rishi Sunak will call a general election for 4 July, Sky News understands.
The surprise move comes after a day of rumours in Westminster the prime minister could go to the country earlier than previously thought.
Follow the latest politics news live - general election to be confirmed
Mr Sunak has been saying for months an election would happen in the "second half of the year" but had refused to set a date.
The assumption in Westminster was that he would call the vote in the autumn, to give his party more time to make up ground against Labour in the polls.
Sir Keir Starmer's party are ahead by about 20 points after he set about transforming Labour following its historic defeat in 2019.
Sky News' political editor Beth Rigby understands that there has been an ongoing "long and open discussion" in Downing Street about whether to hold the election now or in the autumn.
Deputy PM Oliver Dowden in particular has been pushing for a summer election, arguing the improving economic forecast will give the party a fighting chance.
Beth said: "On the back these good inflation figures, the International Monetary Fund upgrading the growth forecasts, the UK coming out of recession, the prime minister looks like he is going to go in the summer."
Speculation Mr Sunak could name the date mounted in Westminster as Cabinet ministers were summoned for an unusually timed meeting on Wednesday, with Defence Secretary Grant Shapps and Foreign Secretary Lord Cameron cutting short trips abroad to attend.
It comes after the Tory leader declared inflation was "back to normal" in a "major milestone" for the country, following official figures showing inflation slowed to 2.3% in April.
Under parliamentary rules, there has to be 25 working days between the dissolution of parliament - at the request of the prime minister - and voters going to the polls.
Read more: The current state of the parties in the polls
As general elections have to be held every five years, the final day a vote could have taken place was 28 January 2025.
However, the Conservatives in 2019 restored the prime minister's power to call an election at a time of their choosing within that five years.
Be the first to get Breaking News
Install the Sky News app for free
The last general election was held in 2019, when Boris Johnson won the Conservatives a landslide over Jeremy Corbyn's Labour Party.
Since then, there have been two more prime ministers, Liz Truss and Mr Sunak, and the Conservatives' 80-seat majority has been reduced.
Keep up with all the latest news from the UK and around the world by following Sky News
Tap hereThis breaking news story is being updated and more details will be published shortly.
Please refresh the page for the fullest version.
You can receive breaking news alerts on a smartphone or tablet via the Sky News app. You can also follow @SkyNews on X or subscribe to our YouTube channel to keep up with the latest news.