Wade, president from 2000 to 2012, has been living in France for the past several months, but was expected to return to Dakar on Monday to lead the campaign for his Senegalese Democratic Party (PDS).
"I will campaign, but not the same way as when I was young," he told a local television station Friday.
A parliamentary victory for the opposition would give Wade the means to obtain an amnesty for his son, Karim, who enjoyed considerable ministerial powers under his father, but was sentenced to six years in prison in 2015.
Karim Wade was also ordered to pay a fine of more than 210 million euros for "illicit enrichment".
He received a presidential pardon in June 2016 and now lives abroad, and an amnesty would lift any doubts over his eligibility in politics, observers said.
Another list of candidates will be fielded by the mayor of Dakar, Khalifa Sall, who has been jailed since March on suspicion of embezzling about $2.9 million in city funds, charges which he has denied.
Sall's lawyers have asked a court to grant him conditional release in order to lead the campaign, ahead of his expected run against the president -- with whom he is not related -- in 2019.
An effort to present a united opposition front fell apart in May over differences between supporters of Wade and those of Sall on who should head the shared list of candidates.
That led to a record 47 lists being presented to voters, up from 24 in the 2012 vote, with 165 seats up for grabs on the July 30 election.
The opposition parties hope to secure a majority that would force President Sall into a "cohabitation" government, which would hamstring his ability to push his agenda through parliament.
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