Ahead of Thursday night's Democratic debate in Houston, two contenders - Sen. Elizabeth Warren of Massachusetts and former congressman Beto O'Rourke of Texas - are trying to make splashes on the high-profile issues of Social Security and gun safety.

Warren rolled out a plan Thursday morning that would boost the monthly benefits of Social Security recipients by at least $200 by increasing what high-earners pay into the system.

O'Rourke called on credit card companies and banks to alter several practices with the aim of reducing the purchases of assault weapons and other firearms at gun shows where background checks are not required.

Warren, whose stock has risen amid the release of a flurry of policy proposals, said in a Medium post that her latest plan would provide a $200-a-month increase in Social Security benefits for current and future beneficiaries.

Other proposed rule changes, she said, would benefit women and caregivers, lower-income workers and public-sector workers, among others, whom she says now face inequities in the system.

Warren is also seeking to change the way the cost-of-living adjustments are calculated to better reflect the expenses older Americans face, including higher health care costs.

"We need to get our priorities straight," Warren said in her post. "We should be increasing Social Security benefits and asking the richest Americans to contribute their fair share to the program."

To pay for her plan, Warren would apply a 14.8 percent payroll tax on annual earnings of more than $250,000. Under the existing law, only earnings of up to a specified maximum, which is currently $132,000, are subject to a 12.4 percent payroll tax.

Additionally, Warren would apply a 14.8 percent tax on investment income for individuals making more than $250,000 a year and families making more than $400,000 a year.

O'Rourke, who has heightened his focus on gun safety in the wake of last month's mass shooting in his hometown of El Paso, issued a call Thursday morning for credit card companies and banks "to halt their practices that allow weapons of war to end up in our communities."

He offered several specific suggestions, including refusing to provide services for the sale of assault weapons. O'Rourke noted that weapons used in several recent high-profile mass shootings were purchased with credit cards.

He also called on financial institutions to refuse their services for the sale of firearms online or at gun shows where background checks are not required. O'Rourke offered that as an interim step until Congress passes legislation tightening rules on background checks for gun purchasers, which he has previously advocated.

O'Rourke also urged banks to stop doing business with gun and ammunition manufacturers that produce or sell assault weapons. He called out Wells Fargo in particular for providing loans and credit to the industry and for serving as the bank of the National Rifle Association.

Warren and O'Rourke are among 10 Democratic hopefuls scheduled to face off in a three-hour debate Thursday night.