NEW YORK (AP) _ Bob Dole and Pat Buchanan were tied for the lead in New Hampshire in all five nightly polls tracking likely voters in Tuesday's Republican presidential primary.

The surveys conducted through Thursday or Friday night generally found Dole with little momentum, up or down. Over the past several days, Lamar Alexander has continued gaining slightly, Buchanan at best only marginally.

In one poll, Alexander was tied for the lead. In two others he edged into third place ahead of Steve Forbes, who has steadily fallen in most surveys and on Saturday hinted a fourth-place finish might prompt him to drop out.

Buchanan surged in New Hampshire polling after he upset Texas Sen. Phil Gramm in Louisiana's limited GOP caucuses on Feb. 6, but apparently got less of a bounce after finishing a strong second to Dole in the Iowa caucuses Monday night.

Alexander, a respectable third in Iowa, has gained the most in New Hampshire tracking polls since then _ an average of about 8 percentage points. Forbes was down by an average of 6 points.

Polls also suggest Buchanan is vulnerable over whether he would be viable as the GOP nominee against President Clinton, and as president. Yet his support is more committed than any other candidate's.

ABC News polling Thursday and Friday nights found that 44 percent of likely primary voters believe Buchanan is too extreme to serve effectively as president, a charge Dole stressed late last week. And 63 percent said Buchanan can't beat Clinton in the fall.

But the CNN-USA Today poll found that 68 percent of Buchanan backers say they support him strongly, compared with 45 percent for Forbes, 41 percent for Dole and 27 percent for Alexander.

Because of when the polls were done, it's unclear yet if the race has been altered by the GOP candidates' debate Thursday night, or by disclosures about Alexander's financial dealings and about two Buchanan campaign aides who stepped aside because of alleged ties to white supremacists.

Tracking polls usually average the results from the last two or three nights' surveys, with overall samples of 500 to 600 voters and error margins of plus or minus 4-to-5 percentage points. Differences in how the polls are done, such as in question wording, can vary results.

Top-line numbers from the latest samplings, and statistically significant changes since the last polling completed before the Iowa caucuses:

_ ABC (Thursday and Friday nights): Dole 29, Buchanan 25, Alexander 17, Forbes 13. Forbes down 10 points over the week.

_ Boston Globe-WBZ-TV (Friday night only, 400 likely voters, by KRC Communications and Research): Dole 25, Buchanan 22, Alexander 18, Forbes 13. Alexander up 13 points since Iowa, Forbes down 7, Buchanan up 6.

_ New York Post-WNYW-TV (Wednesday through Friday nights, by the Zogby Group): Buchanan 22, Dole 21, Alexander 20, Forbes 12. Alexander up 11 points, Forbes down 7 since last Sunday.

_ CNN-USA Today (Tuesday through Thursday, by the Gallup Organization): Dole 28, Buchanan 25, Alexander 20, Forbes 13. Alexander up 9 points since Sunday, Buchanan up 6, Forbes down 12.

_ American Research Group, Manchester, N.H. (Wednesday through Friday; bulletin board service for campaigns): Buchanan 27, Dole 23, Forbes 17, Alexander 12. Buchanan up 8 points last week.

Non-tracking polls conducted last week by the University of New Hampshire and Dartmouth College also found Dole and Buchanan tied for the lead, with Alexander close behind.