Rishi Sunak will call a general election for 4 July, Sky News understands.
The prime minister will make a statement in Downing Street at 5pm, when he is expected to name the date of the vote.
The surprise move comes as the Tories trail Labour by 20 points in the polls, and face being ousted by the Opposition after 14 years in government.
Mr Sunak may be gambling on the fact that the improving economic outlook will give him a fighting chance of winning.
Earlier today, 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.
He 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 would be that he would wait until the autumn to give him more time to deliver on his pledges.
However, speculation Mr Sunak could name the date sooner mounted in Westminster on Wednesday, as Cabinet ministers were summoned for an unusually timed meeting with Defence Secretary Grant Shapps and Foreign Secretary Lord Cameron cutting short trips abroad to attend.
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."
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.
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.
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.
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(c) Sky News 2024: Rishi Sunak to call general election for 4 July, Sky News understands
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