As the Senate takes up the nomination of Dr. Henry Foster as Surgeon General , President Clinton has launched an intensive effort to bolster the Tennessee physician's chances. Sidestepping conservative broadsides about Foster's abortion record, Clinton today declared the 61-year-old obstetrician-gynecologist a "pro-life, pro-choice doctor." Foster will testify Tuesday before the Senate Labor and Human Resources Committee. Senate Majority Leader Bob Dole, who has threatened to block a full Senate vote on the controversial nomination, said the GOP will hammer at the Administration's belated disclosures that Foster had supervised hundreds of abortions. "This is about telling the truth," said Dole. "This is about the White House leveling with the American people and not letting it drip, drip, drip out as the American people find out." For his part, Foster is taking his cues from the world of heavyweight boxing: "Am I intimidated? No. And I'm not being immodest, I'm not being cocky."