Terry Considine, a dapper young businessman, looked like a model candidate for the Republican U.S. Senate nomination in Colorado. He has a ton of his own money, high-powered advisers -- including New York media consultant Roger Ailes -- and connections with many senior Colorado Republicans.

Then Considine started giving speeches, and he's been in trouble ever since.

First Considine said that he had wanted to "tell the truth about Social Security in this campaign," but that Ailes had directed him not to.

Then he blasted the Democratic Senate candidate, Rep. Tim Wirth, for accepting contributions from Wall Street executives who had an interest in legislation pending before Wirth's subcommittee on tele-communications. Colorado newspapers quickly noted that Sen. William L. Armstrong (R-Colo.) had accepted similar contributions in 1984, when his campaign manager was Terry Considine.

Then Considine set forth his position on immigrants from Latin America. But he didn't call them immigrants, he called them "wetbacks." That led to a big front-page headline in The Denver Post: "Considine Apologizes for Racial Slur."

But a $500,000 television advertising campaign can make up for a multitude of sins. The Denver Post poll shows Considine gaining on Rep. Ken Kramer and leading state Sen. Martha Ezzard, his two opponents in the Republican Senate primary Aug. 12. In six months, Considine moved from nowhere to within eight percentage points of Kramer, and from slightly trailing Ezzard to a 26-point lead. Simon For White House?

*Add another name to the list of those mentioned as possible 1988 Democratic presidential candidates: Sen. Paul Simon (Ill.). A few of his congressional colleagues and some union leaders have suggested to Simon that he seriously consider a run. The thinking, according to one person who has spoken with Simon, goes like this: Simon is from a large state, with a large farm population, he is a liberal, but he introduced balanced-budget legislation and he supported Gramm-Rudman-Hollings -- and the field is wide open.

What does Simon say to this? According to his press secretary, David Carle, "He is intent upon being the best senator from Illinois -- at the moment." Kemp: Two More Years

*Rep. Jack Kemp (R-N.Y.) announced Tuesday he will run for a ninth term in Congress, adding that he won't decide until after the 1986 elections whether to seek the GOP presidential nomination in two years.

Kemp said he had "made no secret of my strong interest in pursuing the possibility of a (presidential) run in 1988. I have not, honestly, made that decision. The fact that my name has been prominently mentioned should not direct from my race for the Congress in 1986."

James Keane, a Democrat and a Buffalo city councilman, who is challenging Kemp, does consider it a detraction and intends to make Kemp's national ambitions an issue. Rep. Tony Coelho (Calif.), chairman of the Democratic Congressional Campaign Committee, is lending his support; he has sent a fund-raising letter to 200 political action committees. Gephardt's Grim View

*An early sample of potential presidential candidate Rep. Richard A. Gephardt (D-Mo.) on the stump: "I don't see burgeoning opportunity in America. I see eroding opportunity. It's not morning in America, Mr. President. It's twilight, it may even be midnight, and it's getting darker all the time." Postscript

*Rep. James R. Jones (Okla.) has more cash on hand than any Democratic Senate challenger except Florida Gov. Bob Graham. Jones is fourth in money raised.