A delay in forming a government could push back the start of Brexit talks, now scheduled for June 19, and reduce the time available for what are expected to be the most complex negotiations in post-World War Two European history.
With the complex talks on the divorce from the European Union due to start in 10 days, it was unclear what their direction would now be and if the so-called "Hard Brexit" taking Britain out of a single market could still be pursued.
Facing calls from her own side to resign, May moved fast to try and consolidate her position.
Her office said later that the key finance, foreign, Brexit, interior and defence ministers would remain unchanged. "It's bad. She's in a very hard place".
A very personalized, nearly presidential style of campaigning has contributed to the Conservative Party's loss of support, said Mark Goodwin, lecturer at the department of political science and global studies at the University of Birmingham in England.
"I certainly think that there will be contact made over the weekend, but I think it's too soon to talk about what we're going to do", DUP leader Arlene Foster said, speaking to BBC Radio Ulster.
'Well, this morning it doesn't look like a strong government, it doesn't look like a stable government, it doesn't look like a government that has any programme whatsoever'.
German Socialist party chief Martin Schulz, who used to serve as President of the European Parliament, tweeted a healthy dose of Schadenfreude on Friday: "Whoever makes politics a game, loses".
Rather than an official coalition, the partnership is likely to be on an issue by issue basis. Several Conservative lawmakers, including Scottish Conservative leader Ruth Davidson, raised concerns over the DUP's opposition to same-sex marriage.
May was under pressure to fire her most senior advisers, Nick Timothy and Fiona Hill, blamed by many Conservatives for steering the election campaign toward disaster. He said it was impossible to predict whether she would still be prime minister at the end of the year. There was no landslide one way or the other, but at least one government minister has lost her seat.
May experienced a gradual slide during the campaign period, in which a wide gap between the Conservatives and Labour narrowed.
With the smaller parties more closely aligned with Labour than with the Conservatives, the prospect of Corbyn becoming prime minister no longer seems to be fancy. At the time, polls suggested her party would win with a big majority.
Although called as a Brexit election, the campaign was quickly overshadowed by security as two deadly terror attacks, in Manchester and London, struck.