The center-right National Action Party and center-left Party of the Democratic Revolution are running on a joint ticket with the leftist Citizens Movement (MC) for next July's presidential election, and the income plan is a key part of their manifesto.
Details are still in works
Officials inside the alliance say details of the plan are still being worked out, though its contours are emerging.
A basic income of 10,000 pesos ($537) per year for everyone, including children, could be provided by consolidating funds from federal, state and municipal welfare programs, Jorge Alvarez, an MC congressman working on the plan told Reuters in a recent interview.
"If you multiply that by four or five, which is the typical size of a Mexican family, you get an annual income of 40,000 to 50,000 pesos per family, Alvarez said, adding that providing the income to children could be conditional on school enrollment.
Home to the richest man in Latin America, Carlos Slim, Mexico is laden with oil and minerals, boasts a large manufacturing base and has the world's 15th biggest economy. But poverty has remained stubbornly stuck above 40 percent of the population for decades.
Extra taxes needed?
Government social development agency Coneval defines poverty as a person living on no more than 2,925 pesos a month in cities and 1,892 pesos in rural areas. The agency also takes into account other factors like healthcare and education.
Getting to 40,000 or 50,000 pesos per family could be achieved "without increasing taxes," Alvarez said.
Still, the Organization for Economic Cooperation and Development argues that providing an unconditional basic income to everyone of working age would do little to combat poverty if not funded by extra taxes.
The idea of universal basic income has gained currency due to the increasing robotization of the workforce. Finland is running a pilot project to test whether unconditional payments could serve as a plausible alternative welfare model.
Robots taking jobs
Mexico has seen job growth in recent years thanks to a manufacturing boom, and could face a smaller workforce as robots take over more tasks.
Swiss voters rejected a basic income plan in a referendum last year, while the defeated Socialist candidate in France's presidential election this year, Benoit Hamon, championed it, saying it would be funded by a tax on robots that replace human labor.
Mexican gross domestic product was worth $1.046 trillion in 2016, according to the World Bank, but some 53.4 million Mexicans, or 43.6 percent of the population, live below the poverty line, according to Coneval.