May tried to shore up her besieged leadership with a speech to her party's "1922 Committee" of backbench lawmakers. Many of them oppose her attempts to strike a Brexit agreement with the EU, and some Conservatives have called for her to be replaced.
May made a call for unity to the dozens of legislators who packed a wood-paneled room at Parliament in London. Lawmaker Michael Fabricant said May had urged the party to "hang together" as negotiations with the EU reached their endgame, and many in the room had responded with approval. Journalists in the corridor outside could hear loud table-thumping at regular intervals during May's speech.
Rather than the lion's den that some had predicted, "it was a petting zoo," Fabricant said. The meeting came as Britain's spending watchdog, the National Audit Office, said smugglers and other organized criminals were likely to exploit gaps in border enforcement in the event of a "no-deal" Brexit.
The International Air Transport Association also warned there could be "chaos for travelers" if backup aviation plans weren't put in place quickly. Britain is due to leave the EU on March 29, but London and Brussels have not reached an agreement on their divorce terms and a smooth transition to a new relationship. The stalemate has heightened fears that the U.K. might leave without a deal in place, leading to chaos at ports and economic turmoil.
In its report, the National Audit Office said that political uncertainty and delays in negotiations with the EU have hampered preparations for new border arrangements, and the government is now racing to bolster computer systems, increase staffing and build new infrastructure to track goods.
The office said 11 of 12 major projects may not be delivered on time or at "acceptable quality." "Organized criminals and others are likely to be quick to exploit any perceived weaknesses or gaps in the enforcement regime," it added.
IATA, the international airline trade body, called for urgent planning by Britain and the EU to ensure "the uninterrupted continuation of air connectivity" — in other words, to keep planes flying — and to maintain safety and manage border controls.
Director General Alexandre de Juniac said failure to put such measures in place "could mean chaos for travelers and interrupted supply chains." "A backstop contingency plan to keep planes flying after March must be published, and quickly," he said.
Meanwhile, the Financial Times reported that British Transport Secretary Chris Grayling raised at a Cabinet meeting Tuesday the idea of chartering ships to bring in food and medicines through alternative ports if new customs checks led to gridlock on the main shipping route between Dover in England and Calais in France.
"We remain confident of reaching an agreement with the EU, but it is only sensible for government and industry to prepare for a range of scenarios," the Department for Transport said in a statement. Scottish First Minister Nicola Sturgeon, a Brexit opponent, said the government's "staggering incompetence" made Britain leaving the EU without a deal in place "the most likely outcome."
May said this week that a divorce deal was "95 percent" done, but the two sides still have a "considerable" gap over the issue of the border between the U.K.'s Northern Ireland and EU member Ireland. Britain and the EU agree there must be no barriers that could disrupt businesses and residents on both sides of the border and undermine Northern Ireland's hard-won peace process. But so far, each side has rejected the other's solution.
May has attempted to break the impasse by suggesting that a post-Brexit transition period, currently due to end in December 2020, could be extended to give more time for new trade and customs arrangements.
The EU has said it is open to the proposal, but the idea has infuriated May's political opponents on both sides of Britain's Brexit divide. Pro-Brexit politicians see it as an attempt to bind the country to the bloc indefinitely, while pro-EU politicians say it is a sign of May's weak bargaining hand and an attempt to stall for time.
May's rousing performance before the 1922 Committee — which plays a key role in deciding who leads the Conservatives — may have brought a temporary reprieve. Under Conservative rules, a no-confidence vote in the leader is triggered if 15 percent of party lawmakers write to the 1922 Committee requesting one. The required number currently stands at 48 lawmakers; only committee chief Graham Brady knows how many have been submitted.
Former Home Secretary Amber Rudd said May had addressed the meeting with "passion and emotion," and her job was probably safe for now.
David Rising in Berlin contributed to this story.