Back in 2010, when the tea party tidal wave propelled Republican Marco Rubio into the Senate, it seemed that the seat held by Democratic Sen. Bill Nelson might be easy pickings for the GOP this time around. As the last statewide elected Democrat in Florida, Sen. Nelson, 70, surely makes a tempting target for Republicans.

But two years later, GOP hopes have run headlong into reality. An altered political environment and Sen. Nelson’s record as a centrist on national issues and as an effective advocate for things Floridians care about — stopping coastal drilling, protecting the rights of Medicare recipients, restoring the Everglades — make him a formidable candidate.

Republican challenger Connie Mack IV, 45, is the son of a well-liked former U.S. senator whose seat Sen. Nelson won in 2000 after the elder Mack retired. He is a four-term member of Congress from Florida’s 14th District. Three other candidates dropped out before the August primary that Rep. Mack won, taking 58 percent against former Rep. Dave Weldon.

A conservative, Rep. Mack has often tacked to the right of his own party, voting against a budget bill that passed in the Republican-led House last month by a margin of 329-91 to avert a government shutdown at the end of the fiscal year.

Yet he has found it hard to gain traction against Sen. Nelson, relying on attack ads instead of offering a compelling vision of his own for Florida. Last week’s testy debate, riddled with tit-for-tat accusations, failed to change the race in any significant way.

Sen. Nelson has repeatedly shown an ability to work across the aisle on Florida’s behalf, the kind of voice Florida needs in the Senate. With Republican Sen. Kay Bailey Hutchison of Texas, he successfully co-sponsored the legislation to ensure that NASA would remain committed to a space exploration program. And with former Republican Sen. Mel Martinez of Florida, he co-authored a bill to keep Florida’s beaches safe from oil drilling in the Gulf of Mexico.

Sen. Nelson supported the Affordable Care Act, but only after ensuring that Medicare Advantage was protected under a formula that aids Florida’s senior citizens. Rep. Mack has voted for a Republican plan that replaces the Medicare entitlement with a voucher program for future recipients.

For Florida, Sen. Nelson’s position on coastal waters is the best bet. He led the fight to win reparations from BP for the massive oil spill. And he opposes expanding oil and gas drilling leases in the eastern Gulf of Mexico. Rep. Mack supports drilling off Florida’s coast as long as the military is protected and the state gets revenue.

In an interview with The Herald’s Editorial Board, Sen. Nelson acknowledged the need to break the gridlock in Congress, particularly on debt and budget issues. He favors a balanced approach that raises new revenue and cuts spending, but insisted that he would “not let them pick on Social Security and Medicare” to fix the nation’s finances.

That is the sensible sort of voice that Florida needs in the Senate.

With Democrats and independents outnumbering Republicans in Florida, and the other Senate seat held by a rising GOP star, it’s important to have a Democrat with a proven track record of working in a bipartisan fashion to promote the interests of this “purple” state in the upper chamber.

For U.S. Senate, The Herald recommends BILL NELSON.