"I think we will be successful in the Senate," Brownback said at a news conference Tuesday in Washington.
The senator's amendment is opposed by the Obama administration, consumer groups and the Pentagon. Brownback declined to predict how many votes he could get or how many co-sponsors he could attract.
Brownback spoke as more than 100 dealers from 40 states were meeting with their senators to lobby for the amendment.
The National Automobile Dealers Association spent tens of thousands of dollars to fly in dealers in the last couple of days and pay for their lodging, said NADA chairman Ed Tonkin.
Brownback, who is retiring from the Senate this year and is running for governor of Kansas, said he will talk to Senate leaders Tuesday about trying to attach the amendment to the sweeping financial regulation bill.
The bill, which seeks to prevent a recurrence of the biggest financial meltdown since the Great Depression, is in limbo as Democrats prepare for a second vote Tuesday on beginning debate. They failed yesterday to get the 60 votes needed to bring the legislation to the floor.
The current legislation would place dealer-assisted financing under the oversight of a proposed new consumer financial-protection unit of the Federal Reserve.
"Why do we need another redundant federal agency?" Brownback said. "We shouldn't sweep in Main Street because of a problem on Wall Street."
Brownback said if he could get the amendment attached to the current bill it probably would take 60 votes to have it removed. But if the amendment were voted on by itself it probably would need 60 votes to win.
He declined to predict when Senate leaders would decide how his amendment would be considered.
The financial regulation bill that passed the House exempted dealers from oversight by a proposed new agency.
The new regulator in the House legislation would be an independent stand-alone agency, distinct from the subsidiary of the Fed that the Senate bill provides.
If the Senate bill passes, any differences between it and the House bill would have to be resolved in a conference of leaders from the two chambers.