Labour brought in £2.7m in donations in the crucial first week of May as prominent businessmen continued to pour money into the Conservative Party.
"We will be setting out our policies in the manifesto when we publish it tomorrow", May told a news conference.
Ms Dugdale, the party's leader in Scotland, said she defined success as "winning the election".
"I see leadership as not dictating but leadership is also about listening".
Local Labour campaigner Joe Ashton, 29, said the manifesto set the party apart from others.
She told BBC Radio Scotland: "I think he's wrong, I hope he's wrong". While many of Labour's policies are popular - among them, renationalizing some rail, energy and utility companies - the party faces hard questions about how it plans to fulfill its pledges without large increases in taxes and government borrowing.
Launching the party's election manifesto in Bradford on Tuesday, Jeremy Corbyn said it was a fully costed plan to transform Britain's economy for the benefit of the many.
"Do you not think the British people deserve to see me and you debate live and on television?"
"For seven years the Conservatives have been holding Britain back", the Labour leader said.More news: Wizards-Celtics Rivalry Renewed for the Playoffs
In comments that will incense and dismay many Labour MPs, Unite leader Len McCluskey spoke out just hours after the launch of the party's election manifesto.
"But our votes are being hijacked by Tory and SNP politicians who want to use how we voted in referendums and general elections to assume something about the kind of future we want to see".
The Prime Minister has refused to take part in televised debates, while Labour leader Mr Corbyn has said he will only join in if his main rival for Number 10 is also present.
Labour's councillors in Aberdeen were requested to stand down from the arrangement by 5pm last night but instead formally ratified it at the city chambers.
Both Gordon Brown and Ed Miliband resigned after leading Labour to defeats in 2010 and 2015 but, amid speculation that jockeying for position has already begun, there have been suggestions that Mr Corbyn could stay on if he equals the 30.4% vote share that Ed Miliband got in 2015.
A Labour government at Westminster would also u rge the Scottish Government to hold an inquiry into the actions of Scottish police during the miners' strike.
Labour is defending its plans to exert state control over key utilities amid uncertainty over what the final price tag will be and how it will be paid for.
The Labour leader plans to raise £6.4 billion from the top 5% of earners by lowering the threshold for the 45p rate of income tax from £150,000 to £80,000 and introducing a new 50p rate for earnings above £123,000.
The IFS said: "The tax revenue that Labour's proposal would raise is highly uncertain".