Aides to Mrs. Clinton said a transition back to Senate life was not a chief concern at the moment. “Senator Clinton is focused on running for president and being the nominee,” said a spokesman, Phil Singer.

Yet even if she is once again principally the junior senator from New York, a case can be made that her campaign has strengthened her Senate hand. She is now an even more firmly established national figure in her own right, with a defined and substantial following, one of the few in the Senate who can make that claim.

Her standing will enable her to command attention even though she might lack a clear Senate platform. She will be sought after as a campaign resource (and, should she choose to settle scores, can shun requests from those who did not help her).

“Anyone who thinks she will return to the body in a weakened condition does not understand the nature of politics,” said Senator Lindsey Graham, Republican of South Carolina and a close ally of Senator John McCain, who is proof that losing a presidential primary race is not the end and can even be the beginning.

Mr. McCain, the presumptive Republican nominee, recovered from a stinging presidential primary loss in 2000 to become a Senate force by leading a bipartisan coalition able to control the balance of power on tough issues like judicial nominations. He used his stature as a springboard back to the presidential fray.

But Mrs. Clinton’s relatively junior status limits her options in the Senate. She is pretty far down the ladder on her committees, denying her a chairmanship, the most potent source of influence and bargaining chips in the Senate give-and-take.

Allies have said the Senate leadership should carve out an important niche for her, but that is not easy since any position could come at the expense of a more senior member. Top Democratic officials say the party leadership is not considering any special spot, though lawmakers would not rule out some accommodation if she sought one.