The Prime Minister will move today to confirm the election plan in a clash with Bill Shorten over tax cuts, budget repair and the nat­ion’s economic direction, while Labor attacks with warnings about government cuts to health and education.

Setting up the trigger for an election in 74 days, the Senate voted last night to defeat the government bill to restore the Australian Building and Construction Commission as unions railed against the bill, despite employer demands for greater protections on building sites.

The government gained an important victory over Labor and the unions shortly before 10 o’clock last night by securing Senate support to abolish the Road Safety Remuneration Tribunal, an outcome backed by owner-drivers who objected to wage rates being set in the name of preventing accidents.

Mr Turnbull will prepare for the poll with a series of policy statements in coming days, including a vow to toughen oversight of the major banks, countering Labor accusations that he is “colluding” with the industry to prevent a royal commission into financial scandals. Labor holds a narrow lead in the latest Newspoll as the Opposition Leader accuses Mr Turnbull of slashing essential services, retreating on tax reform and facing internal dissent in the wake of last year’s toppling of Tony Abbott. The Prime Minister is seeking to quell disquiet within his own ranks and appeal to wavering voters with a May 3 budget that is being framed as a blueprint for growth, starting with a major defence announcement yesterday that will cost billions of dollars.

Mr Turnbull and Defence Minister Marise Payne committed to the local construction of a new fleet of patrol boats, declaring they would “directly secure” more than 2500 jobs for decades in South Australia and Western Australia.

This will be followed by a $50bn commitment to a new submarine fleet within weeks, naming a successful bidder from competing Japanese, German and French contractors before the election campaign begins and the government goes into caretaker mode.

Mr Turnbull made no statement last night on the Senate’s decision to reject the government bill by 36 to 34 votes, but Deputy Prime Minister Barnaby Joyce said the upper house had “loaded the gun” for an election.

Mr Shorten declared himself ready to face voters whenever the Prime Minister confirmed the election date. “This will be a contest between Labor putting people first, and a Liberal Party looking after vested interests and the big banks,” Mr Shorten said.

“Australians know where Labor stands and what we stand for: decent jobs, protecting Medicare, better schools, renewable ­energy and a fairer tax system.

“We will campaign on our plans for a growing economy, delivering opportunity for everyone. “Australians are fed up with a Prime Minister who dithers but doesn’t deliver.”

The Attorney-General George Brandis said last night that voters faced a choice between the government’s preference for spending restraint with Labor’s plan for bigger taxes to support new spending.

Senator Brandis argued that there should be no surprise with the latest opinion polls, which includes a Newspoll showing Labor leads the Coalition by 51 per cent to 49 per cent on a two-party-­preferred basis.

“Almost all Australian elections fall within the 52:48 margin — a 53:47 margin is regarded as a landslide,” he told ABC TV after the Senate vote.

“As we move into the home stretch, you would expect the race to tighten because that is what always happens.”

Mr Turnbull will respond to the Senate outcome today by confirming his intention to seek a double dissolution, but he will stop short of calling the election because doing so would leave him exposed to claims that his government had already entered caretaker mode.

Forcing a “phoney campaign” for several weeks, he is not expected to visit the Governor-General, Peter Cosgrove, to request the double dissolution until after the budget.

Holding a double dissolution poll before June 30 would see the incoming senators have their terms backdated to July last year, forcing another half-Senate election before the middle of 2018 and putting the upper house out of sync with the lower house.

Mr Turnbull set up the Senate showdown on March 21 by vowing to hold an election on July 2 if the upper house refused to approve the restoration of the ABCC and the accompanying Registered ­Organisation Act to toughen penalties on union officials who misused member funds.

Adding a third front to this attack yesterday, the government forced through a bill to scrap the Road Safety Remuneration Tribunal on the grounds that its decisions helped unions while harming truck drivers who owned their own rigs.

The Senate rejected the ABCC bill shortly before 6.30pm after hours of debate in which Labor, the Greens and a majority of crossbenchers rejected construction industry pleas for stronger civil powers to ensure industrial peace on building sites.

The government then passed the Road Safety Remuneration Repeal Bill in both the lower and upper house last night. The Registered Organisations Act was not put to a vote yesterday but is already a double dissolution trigger having been rejected three times by the Senate

The ABCC bill was lost after crossbench senators Jacqui Lambie, Glenn Lazarus, John Madigan and Ricky Muir joined with Labor and the Greens to defeat the bill.

The move to take the government bill to its second reading — a stage before final approval — was backed by David Leyonhjelm, Bob Day, Nick Xenophon and Zhenya Wang. Senator Lazarus said he would not be “blackmailed” into supporting the ABCC bill when a broader corruption commission was needed instead, a view held by others including Senator Lambie. “If this ABCC legislation passes, bankers have more legal rights than blue-collared construction workers,” Senator Lambie said.

“This principle of equality before the law is one of the main foundations Australia was built on. It’s one of the reasons why we fought wars against dictatorships in totalitarian countries.”