Independent Secretary of State candidate Greg Ballard has collected more than 20,000 petition signatures toward the roughly 37,000 needed to appear on Indiana’s November ballot, his campaign said Thursday.

Many of those signatures were gathered this week outside vote centers during Tuesday’s primary election, where volunteers worked to capture registered voters as they came and went from the polls.

The former two-term Indianapolis mayor also announced a new volunteer effort, “100 Hoosiers, 100 Signatures,” asking supporters to each commit to gathering 100 signatures from registered Indiana voters. The campaign launched a website, BallardontheBallot.com, where volunteers can download petition forms or request that the campaign mail forms to their homes.

State law requires independent candidates for statewide office to submit petition signatures from registered voters to qualify for the general election ballot. The campaign said its signature count is increasing daily and it remains on pace to meet the threshold.

“We get calls, texts and emails from Hoosiers every day eager to ensure they have a choice in November,” Ballard said in a statement. “This effort is in direct response to Hoosiers asking how they can help the campaign and signals a true grassroots movement.”

As an independent, Ballard did not appear on Tuesday’s primary ballot and must qualify through the petition process. Republican and Democratic voters selected their party nominees for Secretary of State in the primary.

In a notable development on the Republican side, current Secretary of State Diego Morales was not elected as a delegate to the Indiana Republican Party’s state convention, nor was his wife. Republican delegates will choose the party’s nominee for Secretary of State at the convention later this year, meaning Morales will need support from delegates other than himself and his spouse to win renomination.

Ballard served as mayor of Indianapolis from 2008 to 2016. A retired Marine, he won an upset victory in 2007 with no prior elected experience.

The Secretary of State oversees Indiana’s elections division, business services, securities regulation and auto dealer licensing.