By Alex Dobuzinskis

LOS ANGELES – Madonna has always reveled in controversy and with the recent launch of her concert tour, "Sticky & Sweet," the 50-year-old pop star has kicked up a new fuss by comparing John McCain to Adolf Hitler in a video.

The dust-up is the latest in a career of risky moves that have paid off handsomely for Madonna, whose tours and albums have long mixed music with politics, sex and religion. While other stars rose to fame in the 1980s then faded away, "Material Girl" Madonna has become a global star and even courted controversy to stay relevant to younger audiences.

As her world tour opened in Cardiff, Wales, over the weekend, Madonna showed a video montage juxtaposing images of Hitler with McCain, the Republican senator from Arizona running for president against Democratic Sen. Barack Obama. The Democrats on Monday launched their nominating convention.