OTTAWA -- One of the few electoral law experts to give high marks to the Harper government's proposed overhaul of the Canada Elections Act is now offering a much more qualified assessment of the reforms.

Jean-Pierre Kingsley, former national chief electoral officer, said Tuesday that at least two key provisions must be dropped and others changed in order to preserve the integrity of the electoral system.

When Bill C-23 was first introduced, Kingsley gave it a grade of A-minus.

However, he refused Tuesday to say if he'd stick with that grade if his recommended changes are not made.

Moreover, Kingsley told the committee he agrees with the testimony of his successor, chief electoral officer Marc Mayrand, who eviscerated the bill during an appearance before the committee earlier this month.

Canada's election laws are built on the values of "participation, fairness, impartiality, accountability and fairness," Kingsley said, but the bill falls short of those values on several fronts.

Two particular provisions -- eliminating vouching and muzzling the chief electoral officer -- "will impact very negatively on the values of participation, impartiality and transparency" and must be dropped, he said.

Doing away with the practice of allowing people to vouch for voters who don't have proper identification would disenfranchise seniors, aboriginals, youth and transients who don't have adequate ID, Kingsley said.

"This will directly affect the constitutional right to vote of a significant number of Canadians without justification."

He similarly urged the government to drop a provision that would allow the chief electoral officer to communicate with the public only about the mechanics of voting.

"The chief electoral officer must retain the authority to reach out to all Canadians, to speak to them about our electoral democracy, the importance of our constitutional right to vote and the methods and the values at the core of our electoral system," Kingsley said.

"Let me be clear," he added. "Absent the rescinding of the proposed section ... Canadians will lose their trust and their confidence in our elections. That is not acceptable."

Kingsley said other changes are also "essential."

He zeroed in on a provision that would allow political parties to exempt from their campaign spending limits any money spent to raise donations from people who have donated at least $20 over the previous five years.

Making a pitch for donations inevitably involves touting the reasons why donations are deserved "and this can only constitute advertising for or against a party or a candidate," he said.

Moreover, he said such a provision would be impossible to monitor or verify and it would favour richer, established parties, to the detriment of poorer and especially new parties.

Kingsley also questioned why the bill ignored repeated calls by past and current elections watchdogs for the power to compel testimony during investigations of electoral wrongdoing and the power to audit the books of political parties.

His criticism was tempered with praise for some other parts of the bill.

He lauded creation of a mandatory registry for all automated campaign phone calls in an effort to stamp out the kind of fraudulent calls that marred the 2011 campaign. He also praised the proposed increase in penalties for impersonating an elections official.

Thousands of voters complained in 2011 about receiving misleading robocalls from purported Elections Canada officials directing them to the wrong polling station.

The proposed legislation, introduced Feb. 4, would effectively split Elections Canada in two, separating the chief electoral officer who administers the rules from the commissioner who investigates and enforces those rules.

The commissioner would operate out of the office of the director of public prosecutions, who is answerable to the federal justice minister.

Kingsley said the impact on the commissioner's independence and ability to investigate is "neutral," but he suggested the proposed regime would be less cost effective and investigations would likely take longer.