MPs return to work this week after a summer break extended by Prime Minister Stephen Harper's decision to prorogue Parliament. After Wednesday's Throne Speech, each party will be keen to set the tone and get their messages out to Canadians as the parties gear up for the next federal election in 2015.

The Conservatives

With a Senate expenses scandal that continued to make headlines even as lawmakers were off at their cottages, it will be difficult for the federal government to change the channel and get the focus back on its core issue: the economy. But that doesn't mean it won't try.

Wednesday evening's Throne Speech will be chock-full of consumer-friendly measures, including lowering credit-card and domestic cellphone roaming fees and unbundling cable services to allow customers to pick and pay for channels they want.

But will it be enough to deflect the opposition's attempts to keep the Senate scandal front-and-centre, and will it distract the Liberals and the NDP from getting their own messages out to voters?

Scott Reid, a political analyst for CTV News who served as communications director for former prime minister Paul Martin, said the challenge for the federal government is to make its consumer-friendly, appealing-to-the-middle-class message push the Senate scandal out of voters' minds.

This week, the government can control the political discourse, but they have to pass "the salience test," Reid says.

"Can they say and do things that will have in either the near term or at least in the medium term greater traction than the scandals they're confronted with? Because if you can't drown out the chorus of people talking about (Senators) Mike Duffy and Pamela Wallin, it doesn't matter if you have 110 consumer bills of rights, it ain't going to cut it. And that's the big challenge for them."

The problem with the Senate scandal, of course, is that new allegations pop up every few weeks, making it a more difficult problem for the government to escape from.

Chris Cochrane, a political science professor at the University of Toronto, told CTV News Channel in a recent interview that while voters may not be hanging on to every last development in the Senate scandal, it will have an impact if more damaging revelations continue to come out.

"I don't think it's an issue that's going to swing people who support the government en masse away from supporting the government," Cochrane said. "But I think what it does over time is it chips away at the political support base."

Another challenge facing the Conservatives is that they've been in power since 2006, first with two minority governments before winning a majority mandate in 2011.

"The real kryptonite facing an incumbent government is drift," Reid says. "That a Throne Speech happens and it's blinked and looked past and no one pays any attention and it doesn't alter anything. They have got to take control again of the message and of the political agenda."

Unlike a typical Throne Speech, which is usually long on generalities and short on specific promises, the consumer-friendly measures promised in Wednesday's speech are "designed to have a very visceral, literal, tactile impact on people."

But the Conservatives will also be looking to try to "position the opposition parties, and in particular the Liberals, on the wrong side of those issues so that they can wedge them. So that they can say, ‘Look, this is a test of who stands for the middle class. We're passing, they're failing.'"

The New Democrats

While the government may appear vulnerable on the Senate scandal, the opposition parties have their own work to do not only to prevent the Conservatives from reframing the political discourse, but also to get their own messaging out to Canadians.

NDP Leader Thomas Mulcair went across the country with his "Roll Up the Red Carpet tour," talking about his party's plan to abolish the Senate. Although Canadians are concerned with potential misuse of public funds, the idea of starting the process to eventually get rid of the Upper Chamber gained little traction.

The NDP, then, has a few tasks ahead of them. First, they must continue their strong performance in daily question period, asking clear, short, pointed questions about the Senate scandal. But while they are attacking the government, they must also direct some attention at the Liberals, Cochrane says.

"On the one hand, the NDP's job is to stay focused on the government and criticizing the government, but on the other hand the biggest threat to the NDP is probably the Liberals," Cochrane says. "They're competing for the exact same voters across the country, whether it's in cities, whether it's young people, whether it's in Quebec."

The so-called orange wave that installed the NDP in Official Opposition status largely swept through Quebec, where they won 59 of their 103 seats in 2011.

"If the NDP fail to preserve those gains off the island of Montreal in the 2015 election, then they slip back to third place and the moment of hope for the New Democratic movement vanishes," Reid says.

And a year-and-a-half after he won the NDP leadership race, Mulcair has failed to capture Canadians' attention.

"He remains a question mark by and large in people's minds," Reid says. "People are far more curious and excited and intrigued by Trudeau…Mulcair's got to start to interest people."

The Liberals

Meanwhile, after a summer of introducing himself to Canadians and making headlines with his calls to not just decriminalize but fully legalize marijuana, Liberal Leader Justin Trudeau has his own challenges ahead of him.

After assuming the Liberal leadership earlier this year, Trudeau and his party soared in the polls. Support has since cooled slightly and made the competition between the three parties more of a horse race.

"I do expect his popularity has peaked in the sense that he's not going to get any more popular just for being new," Cochrane says. "Now he's going to increasingly have to earn the popularity with policies that appeal to people and also with attacks and criticism of the government that resonate in public opinion."

Trudeau also spent his summer pledging his support for the middle class, including naming his candidate in the yet-to-be-called Toronto Centre by-election, Chrystia Freeland, to co-chair an economic council of advisors. Freeland said addressing a financial "squeeze" on the middle class is one of her top priorities.

With their consumer-friendly Throne Speech, however, the Conservatives are making their own play for middle-class voters. The Liberals, then, have their own two-front war to fight: to challenge the Conservatives on who will best serve the interests of middle-class voters, while chipping away at NDP support.

And they'll have to do it with the Harper and Mulcair "gunning" for their leader, Reid says.

"Both Mulcair and Harper are going right at him, and he's got to preserve what he's got going and he's got to find ways to extend and deepen it," Reid says. Because in the longer term, as Canadians get closer to voting day, Trudeau will have to answer much more significant questions "before they turn 24 Sussex over to him."