MPs are set to return to the House of Commons Monday, following a fall session that saw the ruling Conservatives dogged by controversies, including the ongoing Senate scandal and a faltering economy.

In a lead-up to Parliament’s winter session, Canada Post workers staged a protest in Ottawa Sunday, voicing their opposition to the December announcement that the financially troubled federal agency would be cutting door-to-door mail delivery.

But that’s only one of the issues Prime Minister Stephen Harper and his government are expected to face.

Questions over the Senate expense scandal and the ongoing RCMP investigation are unlikely to die down after months of allegations and revelations about four senators and the Prime Minister's Office.

The NDP has vowed not to ease up on the Conservatives as the RCMP continues its investigation into allegations that several people in the PMO may have been involved in a cover-up designed to protect former Conservative Sen. Mike Duffy.

Among the revelations is that Harper’s former chief of staff Nigel Wright cut Duffy a $90,000 cheque so Duffy could reimburse alleged fraudulent housing expense claims.

“The RCMP investigation into the Prime Minister’s Office is actually worrisome,” NDP House Leader Nathan Cullen said on CTV’s Question Period Sunday.

The Conservatives are also expected to face questions about a sagging economy.

On Question Period, Deputy Liberal Leader Ralph Goodale criticized the government for a poor record on the economy file.

“There needs to be a focus on employment and on job creation, and this government hasn’t done it, the jobs grant (program) has turned out to be a complete fraud,” Goodale said on Question Period.

After a successful trip to the Middle East, the focus for Harper, Conservatives say, will be to stay the course going into 2015, an election year. The upcoming budget is expected to further decrease the deficit, which the government has said will be eliminated by next year.

“The focus of the spring session will be on job creation, economic growth and long-term prosperity, and as a result, of course, the budget will be the cornerstone of that,” Government House Leader Peter Van Loan told CTV News.

The budget is expected to be tabled in mid-February.