We're thankful that Sen. Tim Johnson is recovering well from brain surgery for an arteriovenous malformation that nearly killed him in 2006, but his health is still an issue in his upcoming re-election campaign for the U.S. Senate.

We have no doubt that Johnson's mind is sharp. We have seen that in his brief interviews with the public. And if this was strictly a desk job, he could easily return to his seat.

But it's not.

That point was brought home at the town meeting between officials at the National Science Foundation and scientists from around the country who got together in Washington, D.C., to discuss the future of the proposed Deep Underground Science and Engineering Laboratory in Lead. Sen. John Thune was there. Rep. Stephanie Herseth Sandlin was there. Gov. Mike Rounds was there. Sen. Johnson was not.

Eleven months into his recovery, ongoing recuperation and rehabilitation may not leave as much time for Senate duties. Johnson still does not grant telephone interviews with reporters nor has he resumed weekly teleconference calls, a standard means of regular communications with reporters, that stopped when he fell ill last December.

His mobility is not what it once was. He cannot speak as well. His stamina is returning, but he does not have the strength he once did.

These are concerns and, as such, raising them should not be cause for his supporters to cry that we are unsympathetic. Instead it is an indication that we are, simply, realistic.

Having said that, there still may not be a better candidate to represent South Dakota in the U.S. Senate than Tim Johnson. Flowery oratory was never his strong suit anyway and his long tenure in a place that rewards seniority is certainly a strong argument for his re-election. South Dakota lost political power when it voted former Sen. Tom Daschle out of office in 2004. No doubt, we would lose more without Johnson in Congress.

The 2008 campaign, with all its rigors and demands, will be an excellent yardstick by which to measure whether Johnson is up to the arduous schedule of a U.S. senator. There is nothing inappropriate about raising those questions or in voters demanding answers to them.

If, post-stroke, Sen. Tim Johnson is the best choice to represent South Dakotans in the U.S. Senate, we will wholeheartedly endorse him and encourage voters to re-elect him to office for a third term.

Time, and the coming campaign, will tell.