May, who has regained confidence after winning support for her tough stance on Syria and Russia, will make a statement to parliament on her decision to join the United States and France in Saturday’s strikes in retaliation for a suspected gas attack.
She will repeat Saturday’s assertion that Britain was “confident in our own assessment that the Syrian regime was highly likely responsible” and that it could not wait “to alleviate further humanitarian suffering caused by chemical weapons attacks”, according to excerpts of her speech.
But she will be grilled over why she broke with a convention to seek parliamentary approval for the action, a decision that she and her ministers say was driven by the need to act quickly.
Much of the criticism will come from opposition lawmakers, but the prime minister may also have to work hard to defend her speed of action to members of her own Conservative Party who had wanted parliament recalled.
Jeremy Corbyn, leader of the main opposition Labour Party, has questioned the legal basis for Britain’s involvement.
“She could have recalled parliament last week … or she could have delayed until tomorrow, when parliament returns,” Corbyn, a veteran peace campaigner, said on Sunday.
“I think what we need in this country is something more robust, like a War Powers Act, so governments do get held to account by parliament for what they do in our name,” he told the BBC’s Andrew Marr Show.
Britain has said there are no plans for future strikes against Syria, but foreign minister Boris Johnson warned President Bashar al-Assad that all options would be considered if chemical weapons were used against Syrians again.
Corbyn’s drive for legislation to limit the government’s power to launch future military action may win support in parliament, where some Conservatives have expressed fear of fuelling an escalation in Syria.
Despite winning international backing, May, who has weathered questions over her leadership due to Brexit and party scandals, has a precarious position in parliament after losing the Conservatives’ majority in an ill-judged election in June.
She now relies on the support of a small Northern Irish party, which has supported the action in Syria, and has tried to dodge votes that might not go her way.
Her predecessor, David Cameron, lost a vote on air strikes against Assad’s forces in 2013, with many in Britain wary of entering another conflict, especially after an inquiry concluded that then-prime minister Tony Blair’s decision to join the 2003 U.S.-led war against Iraq was based on flawed intelligence.
It was not clear whether Labour or other opposition parties would be able to force an emergency debate after May’s statement, or whether the speaker in the House of Commons would grant what one party source called a “meaningful vote”.
But in a sign that the government fears it could lose, one lawmaker said on condition of anonymity that the party’s whips, charged with maintaining voting discipline, had made clear that Conservatives should vote with the government.
May will also apply for an emergency debate to give lawmakers “an extended opportunity to discuss the military action”, her office said, in what could be an attempt to draw the sting out of any opposition motion for the same.
James Cleverly, deputy chairman of the Conservative Party, said even if May had recalled parliament, she could not have presented lawmakers with the full range of intelligence because of its sensitivity.
“I think it is absolutely appropriate that the prime minister and the cabinet made this decision,” he told Sky News.
“She will be coming to the House of Commons where she will be questioned by members of parliament, scrutinising her role as prime minister, and that is the appropriate relationship between government, on the one hand, and parliament, on the other.”
Reporting by Elizabeth Piper; Editing by Kevin Liffey