Charlie McMillan, youngest mayor in US in the unincorporated Grimes County community of Whitehall. (AFP)

"The mayor's breakfast is ready," Chad McMillan sings out from the living room of his Texas ranch.

On the menu this morning: a warm bottle of milk and a jar of puree.

Charlie McMillan is no ordinary city official, he's only seven months old and a new face of the anti-abortion movement in America.

The chubby baby became honorary mayor of his Texas community in October with a sweet slogan: "Make America Kind Again."

A twist on US President Donald Trump's catchphrase of making the country great again, Charlie's "agenda" includes patriotism, adoption and "life", referring to the issue of abortion that tends to polarize Americans.

The infant mayor's emergence comes amid mounting anxiety among abortion rights advocates who fear the 46-year-old Roe v Wade Supreme Court decision that effectively legalized abortion is under threat.

Mayor Charlie McMilla is held by his father Chad McMillan at their home in Whitehall, Texas. (AFP)

"One of his campaign platforms focuses on the brave and courageous choice that... his birth mother made for life," said Charlie's adoptive mother Nancy Jane McMillan.

"She was in the midst of a crisis pregnancy and chose not to terminate the pregnancy but to carry him, and we were the incredibly blessed recipients of that brave and courageous choice."

Charlie's parents bought the honorary mayor title at an auction in October as part of a fundraiser for firefighters in their community of Whitehall, about an hour northwest of Houston.

The appointment, which does not involve any actual duties, was "just something fun that we were doing," McMillan said.

But then the 43-year-old real estate agent realized the influence that "Mayor Charlie" had on the people of Whitehall.

"Just a little bit of kindness goes such a long way, and in this time of political and cultural divisiveness in the United States, it's neat to see how a baby, a seven-month-old, with a campaign promise to make America kind again, can, we believe, impact change."

Charlie's parents are on the development board of the Houston Pregnancy Help Center, a Christian organization that steers women with unplanned pregnancies away from abortion.

Not a Democrat, not a Republican

The inauguration of the country's littlest mayor took place on December 15, with a big party featuring hot dogs, country music and a ceremony for the tuxedo-clad baby.

Local business owner Frank Pokluda said he gave Charlie the oath of office, "and naturally he nodded each time so he was well aware of what he was doing."

"Look at the joy this child has brought to this community... there's people out there who'd love to have these kids so I think it's a great thing," he added.

Advocates for women's reproductive rights argue that access to abortion is vital for gender equality and the reduction of poverty and many other societal ills.

Outlawing terminations simply drives patients underground, they argue, where operations are unregulated and potentially deadly.

Chad McMillan, 51, hopes his son can provide a much-needed respite from the political battles that have divided the country.

"We hope that Charlie, who isn't a Republican, who isn't a Democrat, who isn't an independent, who loves people, can allow everybody to take a breath," said the Baptist pastor and missionary, who voted for Trump in 2016.

That could prove difficult with the Supreme Court to rule in the first half of 2020 on a Louisiana law that critics say would force the closure of most of the state's abortion clinics.

Several states this year tightened abortion access, making the procedure illegal when fetal heartbeat is detected, although courts struck down several such laws.

Trump campaigned on a pledge to appoint only opponents of abortion to the Supreme Court. He has named two of the court's nine justices, leaving the bench with a 5-4 conservative majority.

Abortion opponents are counting on the new justices to help overturn Roe v Wade, or at least allow states to restrict access to the procedure.