Indiana Gov. Mitch Daniels continues to keep the political world waiting, saying recently that he will announce “within weeks” whether he will run for president in 2012.

The Republican’s decision — which could come as soon as Thursday at the Indiana Republican Party’s spring dinner, where his wife, Cheri, will be the keynote speaker — could have an impact well beyond just one man saying yes or no, however.

The GOP presidential race has been defined by relative chaos — and weakness — among the field.

That was reinforced at last week’s first presidential debate of the season, which, aside from former Minnesota governor Tim Pawlenty, featured a handful of long shots and no-shots debating such topics as the legalization of marijuana — and even heroin.

Daniels is regarded (and regards himself) as a candidate of considerable gravity, willing to focus on making tough choices about the nation’s financial future even if that conversation is politically unpopular. (At a February speech at the Conservative Political Action Conference in Washington, he said that “purity in martyrdom is for suicide bombers.”)

A Daniels candidacy probably would be taken as a sign that the games are over for the Republican Party, that it is time to buckle down and organize to beat President Obama.

“He will turn a race that is about less serious politics into a race about more serious policy,” argued Alex Castellanos, a Republican media consultant who is not aligned with any candidate heading into 2012. “Daniels is the adult in the room saying the party is over, it’s time to clean house. That contrast in maturity is how a Republican beats Obama.”

The president has acknowledged as much about Daniels, telling an Indiana television station that the governor is “a serious person” before adding: “I have some significant philosophical differences with him.”

Should Daniels opt not to run, on the other hand, the unpredictability that has ruled the race would almost certainly continue unabated.

A field without Daniels — as well as Mississippi Gov. Haley Barbour, who in a major surprise last month decided against running — would mean a race that remained in considerable flux as candidates considered sideshows at best (Donald Trump, anyone?) dominated headlines and complicated GOP efforts to convince the public that the party can present a credible alternative to Obama.

“So far, the most recognizable Republican candidates are unable to seriously begin to define the Republican debate for president,” said former congressman Tom Reynolds (N.Y.). “That will keep the GOP presidential sweepstakes looking like it is still trying to find its way.”

To be sure, Daniels’ entrance into the contest shouldn’t be overstated. He would force a more sober tone but almost certainly wouldn’t end the circus-like atmosphere entirely either.

Obama is already moving to capi­tal­ize on the uncertainty of the Republican lineup.

Publicly, he is casting himself as the one person who, in matters of domestic and foreign policy, is willing to take on the major problems that face the country.

Behind closed doors, his fundraising operation is humming as the campaign seeks to meet — and probably beat — the $750 million that Obama raised as a candidate in 2008.

And next month will be a big one for the Republican presidential race. The next GOP debate is set for June 13 in New Hampshire, and just three days later the Republican Leadership Conference will open in New Orleans, a gathering that will feature virtually every candidate mentioned for national office.

Given all that, what Daniels decides may well serve as a telling signal of whether Republicans are ready to get serious about beating Obama.

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