By Alistair Smout and Amanda Ferguson
LONDON/BELFAST (Reuters) - British Prime Minister Theresa May secured a deal on Saturday to prop up her minority government but looked increasingly isolated after a botched election gamble plunged Britain into crisis days before the start of talks on leaving the European Union.
Her Conservatives struck an outline deal with Northern Ireland's Democratic Unionist Party (DUP) for support on key legislation. It was a humiliating outcome after an election that May had intended to strengthen her ahead of the Brexit push.
Instead, voters stripped the Conservatives of their parliamentary majority. As May struggled to contain the fallout, her two closest aides resigned.
Newspapers said foreign minister Boris Johnson and other leading party members were weighing leadership challenges. But Johnson said he backed May.
May called the early election in April, when opinion polls suggested she was set for a sweeping win.
May's aides, Nick Timothy and Fiona Hill quit on Saturday following sustained criticism within the party of the campaign.
Gavin Barwell was named new chief of staff. The Conservative lawmaker who lost his seat on Thursday and has experience working as a party enforcer in parliament.
The change was unlikely to significantly quell unrest within the party. Most of May's cabinet members have kept quiet on the issue of her future, adding to speculation that her days as prime minister are numbered.
A YouGov poll for the Sunday Times newspaper found 48 percent of people felt May should quit while 38 percent thought she should stay.
The DUP, whose 10 seats in the new parliament give May just enough support to pass legislation, agreed in principle to a "confidence and supply" arrangement, Downing Street said.
That means it will support a Conservative minority government on key votes in parliament without a formal coalition deal.
A source close to the DUP said the party was seeking more funding for the province and concessions for former British soldiers in exchange for supporting May.
Still the deal with the DUP risks upsetting the political balance in Northern Ireland. It aligns London more closely with the pro-British side in the divided province, where a power-sharing government with Irish nationalists is suspended.
The Observer newspaper said the DUP arrangement fell short of a full coalition agreement because of concerns among some Conservative lawmakers about the socially conservative DUP's positions on gay rights, abortion and climate change.
The turmoil engulfing May has increased the chance that Britain will fall out of the EU in 2019 without a deal. Previously, she said she wanted to take Britain out of the EU's single market and customs union in order to cut immigration.
Her party is deeply divided over what it wants from Brexit. The election result means businesses still have no idea what trading rules they can expect in the coming years.
EU Budget Commissioner Guenther Oettinger said it may now be possible to discuss closer ties between Britain and the EU than May had initially planned, given her election flop.
"For instance, if London were to stay in the customs union, then it would not have to renegotiate all trade agreements," he told the Frankfurter Allgemeine Sonntagszeitung newspaper.
The pound on Friday fell 1.7 percent against the U.S. dollar <GBP=> and 1.4 percent against the euro <EURGBP=>.
After confirming on Friday that her top five ministers, including Chancellor Philip Hammond, would keep their jobs, May must name the rest of her team, who will take on one of the most demanding jobs in recent British political history.
May has said Brexit talks will begin on June 19 as scheduled, the same day as the formal reopening of parliament. She confirmed this to German leader Angela Merkel in a phone call on Saturday.
She also reiterated that she would seek a reciprocal agreement early in the talks on rights of EU and British citizens, Downing Street said.
Elmar Brok, a German conservative and the European Parliament's top Brexit expert, told the Ruhr Nachrichten newspaper that the two-year talks would now be more complicated.
"May won't be able to make any compromises because she lacks a broad parliamentary majority," he said.
"SHE'S STAYING - FOR NOW"
Britain's largely pro-Conservative press questioned whether May could remain in power.
The Sun newspaper said senior members of the party had vowed to get rid of May, but would wait at least six months because they feared a leadership contest could propel the Labour party into power under Jeremy Corbyn, who supports renationalisation of key industries and higher taxes for business and top earners.
Survation, the opinion polling firm that came closest to predicting correctly the election's outcome, said a new poll it conducted for the Mail on Sunday newspaper showed support for Labour now 6 percentage points ahead of the Conservatives.
"She's staying, for now," one Conservative Party source told Reuters. Former Conservative cabinet minister Owen Paterson, asked about her future, said: "Let's see how it pans out."
May had repeatedly ruled out the need for a new election before changing her mind. Labour stunned even its own supporters by taking enough seats from the Conservatives to deny them a majority.
The Times newspaper's front page declared that Britain was "effectively leaderless" and the country "all but ungovernable".
"The Conservatives have not yet broken the British system of democracy, but through their hubris and incompetence they have managed to make a mockery of it," it said in an editorial.
If May is to honour the wish of the 52 percent of voters who opted last year to take Britain out of the EU, she must find a way to bridge the differences within her party.
Its eurosceptic wing has long been a thorn in the side of Conservative prime ministers. On the other hand, pro-Europe Scottish Conservative leader Ruth Davidson said she wanted to be involved in "looking again" at Britain's aims for Brexit.
Davidson was one of the few Conservative success stories in the election as the Scottish wing of the party won 13 seats.
She has said she favours retaining the greatest possible level of access to Europe's single market. Davidson also said she had received reassurances from May that the party's deal with the DUP would not involve a rollback of gay rights.
(Writing by William Schomberg and Kate Holton; additional reporting by Alistair Smout, Costas Pitas, Kylie MacLellan and David Milliken in London, Andrea Shalal in Berlin; Editing by Kevin Liffey and David Gregorio)