Paul Goodland is the mayor of Ames, Iowa (pop. 46,300), the rector of Ames' Episcopal Church and an erstwhile supporter of Bob Dole. He's having a moment of celebrity now because he has been converted to the cause of George Bush. The issue? Support of the INF Treaty that Ronald Reagan signed last week with Soviet leader Mikhail Gorbachev.

Goodland does not belong to any of the many peace groups that flourish in the state that votes first, in precinct caucuses, on Feb. 8. But he believes in arms control, and he thinks that the United States should give Gorbachev a little support "at a time when he needs it so much at home."

It wasn't easy for Goodland to desert Dole, whom he has admired for a long time for his strength and leadership. He watched Dole "pull himself out of his hatchet-man phase" and applauded him for his "humility."

But Dole lost him when he began waltzing around on the ratification of the INF Treaty during the Dec. 1 all-candidates' debate at Washington's Kennedy Center. Dole said rather crankily that he had to "study" the treaty before making any decision. After a meeting with Gorbachev, Dole said he supported the treaty "in principle," but in a later New Hampshire appearance he said he was "not quite ready" to vote for ratification.

"This is not a time for fence-straddling," Goodland said. "At the critical point of leadership, he dropped it, and he can't pick it up."

Before he announced what the Dole people regard as his "defection" -- he prefers "conversion" -- Goodland called the Dole headquarters in Des Moines to explain his switch. Tom Synehorst, Dole's regional director for Iowa and Kansas, tried to reach Goodland, but he did not return the call "because it was long-distance, and I did not think it was a good use of the funds I have at my disposal."

The latest NBC poll shows that Dole leads Bush by 42 to 26 percent in Iowa. The state is hostile to President Reagan because of farm policies that are blamed for suicides and foreclosures. But the peace issue could change all that, Bush supporters say, because rural Iowa, which is now on the mend economically, is strongly pro-peace.

Dole, naturally, hopes that Goodland is an isolated case, and that enmity towards the president will more than balance disapproval of his dithering on the treaty. But Rep. Jim Leach (R-Iowa), a Bush partisan, thinks that the INF Treaty could bring the beginning of a Bush resurgence.

"George's ties to the president have been a liability," said Leach, "but on this, they give him an advantage. Iowa farmers and small business people know that arms control not only reduces the danger of war but is a way of getting federal spending and interest rates under control."

Bush, according to Leach, got "exceptional" crowds and enthusiasm last weekend, especially when he said that if elected, he would hope to negotiate other arms control treaties with the Soviets -- on chemical weapons. He once broke a tie in the Senate to vote for chemical weapons.

Dole obviously hopes to disarm the right wing by his show of reluctance on the treaty. Conservatives are organizing a campaign against ratification, under the banner of the Anti-Appeasement Alliance.

If the president decides to campaign for the treaty, Bush, the only Republican candidate committed to it, could benefit even more.

Reagan came down from the summit to a whole new landscape. He is being excoriated by the right and applauded by the left. Liberal Democrats are defending him in Congress, while GOP loyalists sulk in the cloakrooms.

Rep. Byron L. Dorgan (D-N.D.) took the floor twice last week in the unaccustomed role of Reagan champion. The day the treaty was signed, Dorgan advised the president: "Stay strong. Pay no heed to the extremist critics."

For Republican congressional leaders, it is a bitter time. "They have been pretty careful," Dorgan said. "They understand that people overwhelmingly support arms control, so they keep the grumbling and rancor behind the scenes."

As for the president, he is seeing the beginnings of a bipartisan foreign policy, a goal that has eluded him since 1981. The summit brought him kudos he never expected to hear, from the wrong people, of course, but also a return to the popular approval that was ravaged by the Iran-contra scandal.

He knows that the INF Treaty was just a snack. He is looking forward to the main course in Moscow when the 50 percent reduction in strategic weapons may become a reality and he steps forward as the world's premier dove. It's not bad for a politician who in his first bid for the presidency had to beat back the "warmonger" rap.