PARIS — There is something odd about the pointed political debate under way in France about an estimated 15,000 to 20,000 Roma migrants, mostly from Romania and Bulgaria, who, depending on who’s talking, are either a menace to society or victims of systematic discrimination.

Turn on the television, or open a newspaper, and you will see no shortage of strongly held opinions. Even the governing Socialist Party is sharply divided. Last month, Manuel Valls, the minister of the interior, said flatly that the foreign Roma — distinct from France’s estimated 350,000 native Gypsy, or “traveler,” population — are incapable of integrating into society and should go home. He was swiftly denounced by another cabinet minister who accused him of stigmatizing an entire ethnic group.

And so the debate continues, with both sides, each backed by small armies of editorialists and experts, talking past each other and over the heads of the Roma themselves. With six months to go before France’s critical municipal elections, many politicians, mostly on the right (plus Mr. Valls), blame the Roma for a rise in petty crime, a major factor in the overwhelming popular support — 77 percent, according to one poll — for the interior minister’s hard-line position.

They point to assorted statistics like a 69 percent increase, between 2009 and 2011, in crimes committed by Romanian citizens (by law, French statistics do not identify ethnic groups like the Roma) and the 23 percent of crimes committed by minors in Paris in 2010 attributed to young Romanians.