Silver Spring (near Washington), June 21, 1856.

MY DEAR SIR,—I am not strong enough for public speaking, even if I were strong enough for a journey to Boston. Besides, my duties in the Senate have the first claim upon me, and to them I must give my first returning strength. Therefore am I constrained to decline the invitation with which you have honored me.

But I am strong enough to send from my present retreat a brief expression of cordial concurrence in the nominations made by the People’s Convention at Philadelphia, and also of the gladness with which I shall support them, by voice and vote, with mind and heart.

I have long honored Colonel Fremont for his genius in geographical enterprise, his eminent intelligence, his manly fortitude, his perfect integrity, and his easy command of men,—swaying to his own beneficent purpose even the savages of the forest, while Nature herself, in her winter fastnesses, bowed before his march. It is well, at this moment, when a Great Crime is instigated and sustained by the National Government, that such a man, with courage which will not be questioned, and with sensitiveness to right which will not rest, should be summoned to grapple with the wrong-doers. And permit me to say that I find no force in the objection that he has never been a politician.

Your candidate for Vice-President is worthy to enjoy the same enthusiastic support. As lawyer, as judge, and as Senator, Mr. Dayton has been conspicuous for character and ability; and I rejoice to believe that he will soon have a larger field of activity, where these can be employed for the good of our common country, while the Senate, which is the stronghold of Human Slavery, will be compelled to receive as its presiding officer a representative of Human Freedom.

But better even than the candidates is the Declaration of Principles, under which we now go forth to conquer. Such a Declaration, promulgated by such a Convention, is in itself the beginning of victory. Strong in simplicity and truthfulness, it must prevail just so soon as it is comprehended. It expresses objects which should enlist the Conservative, while they enlist the Reformer,—which should rally all who turn with respect to the example of the Fathers, while they rally all who are filled with aspirations for a brighter future on earth. It proposes to save Kansas from the revolting usurpation established in that fair Territory, and in this good work it joins issue with the Slave Oligarchy, now swaying our whole country; so that, in saving Kansas, we shall necessarily overthrow this Despotism, and save ourselves. For support, it appeals to all, without distinction of party, who love their country. It appeals to the true Democrat, whose democracy is founded on the recognition of Human Rights; it appeals to the true Whig, who is animated by that hatred of despotic power which inspired those who earliest wore the name; it appeals to the true American, who is ready to forget all other questions for the sake of union to save Liberty endangered; and it appeals to the foreign-born, who, rejoicing in the privileges of American citizens, will not hesitate to join in this holy endeavor to vindicate them against the aggressions of an Oligarchy worse than any tyranny from which they have fled. In this appeal all former differences are forgotten, while men,

“Erewhile that stood aloof, as shy to meet,

Familiar mingle here, like sister streams

That some rude interposing rock has split.”

In this contest there is every motive to union, and also every motive to exertion. Now or never! now and forever!—such was the ancient war-cry, which, embroidered on the Irish flag, streamed from the Castle of Dublin, and resounded through the whole island, arousing a generous people to new struggle for ancient rights; and this war-cry may be fitly inscribed on our standard now. Arise now, or an inexorable slave-driving Tyranny will be fastened upon you. Arise now, and Liberty will be secured forever.