Saturday's constituency office protests and Monday's website "blackout" are among the ways Canadians are registering their discontent with the Harper government's omnibus budget legislation. (leadnow.ca)

Since the government tabled its budget implementation bill on April 26, federal opposition parties, provincial premiers, the parliamentary budget officer, policy experts and a growing number of environmental groups have expressed concern with the omnibus legislation.

While some of the more populist measures – such as an increase in the duty-free limits on goods purchased south of the border, the elimination of the penny, and the phasing out of the SIN card – were welcomed, other changes have not seen the same support.

The budget bill has elicited negative reaction to its more controversial measures: changes to environmental regulations, employment insurance reform, or an increase in the age of eligibility for Old Age Security benefits.

Here are five ways Canadians are registering their opposition to Bill C-38:

1. 'Black Out, Speak Out' campaign

On Monday, federal opposition parties have joined a coalition of a dozen environmental groups, close to 18,000 individual Canadians, and over 400 organizations in blacking out their websites in a symbolic protest of the government's proposed changes to environmental laws and what they see as the government's attempt to "silence" proponents of environmental causes.

As these websites go dark in support of the 'Black Out, Speak Out' campaign, Natural Resources Minister Joe Oliver and nine Conservative cabinet ministers are fanning out across the country to promote the government's plan for "responsible resource development."

2. 'Stop The Budget' Facebook campaign

This social media campaign is calling on Canadians to write to their MPs asking that they "call in sick" on the day of the final budget vote.

Heritage Minister James Moore's Vancouver-area office was among 74 locations targeted by the leadnow.ca budget protests. (leadnow.ca)

More specifically, the campaign is urging Canadians to write in to nine specific Conservatives MPs from Ontario whom they say missed the first budget vote for one reason or another.

Their hope is that these same MPs might consider missing the final vote again or voting against Bill C-38 altogether.

3. Constituency office protests

On Saturday, Canadians gathered at MPs' offices across Canada in a "Blackmark Day of Action" to protest the omnibus budget bill.

Jamie Biggar, the executive director for leadnow.ca – the non-partisan, independent advocacy organization that organized the rallies – said "if Bill C-38 passes unchanged, it will put a black mark on Canadian democracy."

The group says more than 2,000 Canadians in 74 locations "from Halifax to Whitehorse to Vancouver South" turned out, which was a "higher than expected" participation.

Biggar told CBC News on Sunday more rallies are planned in the coming weeks.

Protesters outside Foreign Affairs Minister John Baird's office in Ottawa joined in Saturday's budget protest. (leadnow.ca)

The rallies were inspired by Conservative MP David Wilks, who was videotaped telling his Kootenay-Columbia constituents that he and other Tory backbenchers were troubled with their own government's budget bill and that he would consider voting against it if 12 other Conservatives MPs were willing to do the same.

Moments after the video went viral, a statement on his web site said Wilks wished to "clarify" his position, and that he was in support of Bill C-38.

4. Opposition in the Commons

The sub-committee tasked with examining the part of the budget implementation bill that deals with changes to the environment, natural resources and fisheries (part 3 of Bill C-38) is expected to table its report to the House of Commons finance committee on Monday.

In an interview with CBC News, NDP Deputy Leader and environment critic Megan Leslie said that "very likely the Opposition will have a dissenting report."

NDP Leader Tom Mulcair said previously his party was looking at all "parliamentary and legal options" to ensure the Conservatives don't shut down the debate over the budget bill. According to Leslie, the NDP is still "weighing their options."

In a separate effort, the Liberals are joining forces with Green Party Leader Elizabeth May to table more than 200 amendments to the bill when it returns to the Commons at report stage. Because May does not sit on the committee reviewing the legislation, she can introduce amendments at report stage.

If that happens, some 50 or 60 hours of consecutive voting could be required in the House of Commons to deal with all of the amendments.

The Conservatives have made it clear they intend to pass C-38 before the summer break. They've already used time allocation once, to limit the amount of time the full House of Commons debated the bill before it was sent to committee for additional review to seven days.

5. Opposition in the Senate

Liberal Senate Leader James Cowan has launched an online petition that calls on Conservatives in the Senate to support Cowan's May 8 motion to send the Conservative-initiated Senate inquiry looking into funding for Canadian charitable organizations to the Senate's finance committee. Cowan told reporters on Monday morning that 5,000 Canadians have signed the petition so far.

Cowan believes Canadian charities would have "the chance to defend themselves against Conservative attacks" if the committee picked up the investigation. Since the inquiry began last February, speeches by Conservative Senators have used most of the allocated time to attack environmental groups.

Environment Minister Peter Kent has accused environmental charities of "laundering" money for foreign foundations.

Bill C-38 proposes amendments to the Income Tax Act and the rules surrounding the political activities of charities. The Senate inquiry could eventually lead to further changes in the Canada Revenue Act.