Southern Arizona’s special election to replace Rep. Gabrielle Giffords in Congress continues to be heavily influenced by national parties based in Washington D.C.

The National Republican Congressional Committee has released a new TV ad once again linking Democrat Ron Barber and the Democrat-backed Affordable Care Act of 2010, approved with the support of Barber’s former boss, Giffords.

As I wrote about in this Sunday story, the issues of Medicare and Social Security are dominating the race to replace Giffords, which pits Barber against Republican Jesse Kelly. More than $1 million has been spent already on attack-style TV ads focused almost entirely on the candidates’ positions on Medicare and Social Security.

The National Republican Congressional Committee has committed $600,000 in ad buys through June 4 in the CD8 special election, said spokesman Daniel Scarpinato.

Kelly and Republicans have released several TV ads — not to mention dozens of press releases — telling voters that Barber is bad for seniors because he supported “Obamacare” which includes more than $500 billion in future spending cuts to Medicare.

Barber, of course, did not vote for or against “Obamacare” and has said he would reform parts of the law. But he was Giffords’ longtime district director and is her chosen successor, and the GOP regularly reminds voters of the link.

“We’ve already learned that Ron Barber supported ‘Obamacare’,” the narrator says. “But what does that mean here in Arizona?”

The ad then refers to more than 342,000 Arizona seniors who “could lose some of their Medicare coverage because of the law Ron Barber supported.”

That’s a reference to the number of people on Medicare Advantage plans, which are operated by private insurers and approved by the Centers for Medicare and Medicaid Services. The Affordable Care Act includes an estimated $145 billion in cuts over 10 years to Medicare Advantage plans which will come by reducing pending per person down to levels that are spent in the traditional Medicare program by paying medical providers less.

The latest government figures show that there are actually 368,000 people in Medicare Advantage today in Arizona. There are In the nearly 107,000 people on Medicare Advantage in the four counties Congressional District 8 touches — Pima, Cochise, Pinal and Santa Cruz counties.

That’s 42 percent of all people on Medicare, which is a higher percentage than both the state and the nation. There are 38 percent statewide and 27 percent nationwide, government figures for April 2012 show.

As past TV ads have, the 30-second spot includes pictures of President Barack Obama and House Minority Leader Nancy Pelosi, D-Calif.

“Ron Barber will help them,” the narrator says as pictures of Obama and Pelosi appear. “But, he will hurt Arizona seniors.”

The Republican ad comes on the heels of a TV ad from the Democratic-House Majority Pac that paints Kelly as too extreme for Arizona, based on his past comments about wanting to privatize Social Security and phase out Medicare.

Democrats have been reminding voters about Kelly’s past comments daily. They slam his pledge this go-round to protect the programs as a disingenuous trick.

Early voting in this CD8 special election begins Thursday. Election night is June 12.

Stay tuned to the Pueblo Politics blog throughout 2012 for news, updates and information about Arizona politics. You can follow Arizona Daily Star reporter Brady McCombs on Twitter by clicking on his name.