Vulnerable incumbents like to tout their clout. This campaign season, they will ask voters: “Do you want to lose all of my power and seniority and be stuck with an ineffective freshman?”

The clout argument is powerful but does not always work. Take former Minority Leader Tom Daschle (D), who rightly argued that his Senate position would help South Dakota, but voters cared more about other factors. Or former Senate Finance Committee Chairman Bill Roth (R), who lost to Democrat Tom Carper in Delaware in 2000.

And sometimes clout is stressed in indirect ways. Sen. Lisa Murkowski (R) ran ads in Alaska asserting that a vote against her could change party control of the Senate, thereby denying Sen. Ted Stevens (R) his powerful committee chairmanship, the Appropriations Committee, which Stevens would lose anyway because of the six-year chairman term limits, although he would be eligible to chair Commerce, another important, but somewhat less powerful, committee. Got it?

The clout argument is especially cogent in Senate races, where seniority matters in determining committee chairmanships and assignments.

First-term senators rarely chair committees; one exception is Sen. Saxby Chambliss (R-Ga.), who chairs the Agriculture Committee, but only because the more senior Sens. Richard Lugar (R-Ind.), Thad Cochran (R-Miss.), Mitch McConnell (R-Ky.) and Pat Roberts (R-Kan.) have other chairmanships or leadership positions. As for committee assignments, it is almost impossible for first-term senators to get onto the plum Appropriations and Finance committees.

Here is an assessment of the current and future clout of vulnerable Republican senators, listed in order of their seniority:

• Montana’s Conrad Burns (31st out of 100) sits on the Appropriations Committee, where he chairs the Interior Subcommittee, which is important to Western states. He is next in line to chair the Commerce Committee in 2010, when Stevens will have to step down.

• Mike DeWine (46th) of Ohio sits on the Appropriations Committee. He is also poised to be chairman of the Intelligence Committee in 2008, as Pat Roberts will have to step down, and as Orrin Hatch will likely chair the Finance Committee.

• Jon Kyl (47th) of Arizona is the Republican Policy Committee chairman and may move up to be conference chairman or even assistant majority leader if Sen. Rick Santorum (R-Pa.) loses his reelection bid and Sen. Trent Lott (R-Miss.) does not jump into the race. Kyl also sits on the Finance Committee, and he or DeWine could someday chair the Judiciary Committee.

• Santorum (49th) is the Republican Conference chairman, the No. 3 position in leadership. If he is reelected, he would likely move up to be the assistant majority leader. He also sits on the Finance Committee and could chair the Rules Committee if he leaves leadership and if Lott steps aside.

• Lincoln Chafee (70th) of Rhode Island could chair the prestigious Foreign Relations Committee someday. In 2008, Lugar must surrender the chair and Chafee will sit only behind Sen. Chuck Hagel (R-Neb.) in seniority.

• Jim Talent (80th) of Missouri has the least seniority of this group but could chair the Agriculture Committee in the future when Chambliss hits chairman term limits and if Roberts does not seek this chairmanship when he steps aside as Intelligence Committee chairman.

In an election year when Republicans may be running against a national tide, we may hear a lot about how Washington clout will bring benefits home.

Fortier is a research fellow at the American Enterprise Institute.