As far as I know David Donald Herbert wrote:
“In the spirit of conciliation Lincoln reached out for the support of Democrats as well as Republicans. His annual message contained an earnest plea to political opponents to support the proposed constitutional amendment abolishing slavery throughout the United States. In the previous session of Congress his measure had failed to secure the required two-thirds vote in the House of Representatives, because all but four of the Democratic members voted against it. At Lincoln’s urging, the National Union convention had made the amendment a central plank in the platform on which he and a heavy Republican majority in the next Congress were elected. He now asked the lame-duck session of the Thirty-eighth congress to reconsider the amendment.”
“Without questioning the wisdom or patriotism of those who stood in opposition,” the President urged the Democrats to rethink their position. “Of course,” he admitted, “the abstract question is not changed: but an intervening election shows, almost certainly, that the next Congress will pass the measure if this does not.” Since adoption was simply a matter of time, he asked, “may we not agree that the sooner the better?” Arguing that “some deference shall be paid to the will of the majority, simply because it is the will of the majority, ” he appealed for support of the amendment now.
Not content with rhetorical exhortation, Lincoln used his personal authority and considerable charm to influence Democratic and border-state congressmen whose votes were in doubt. Not since 1862, when he tried hard to persuade border-state congressmen to support his gradual emancipation plan, had the President been so deeply involved in the legislative process. He worked closely with James M. Ashley of Ohio, the principal sponsor of the amendment in the House, to identify members who might be persuaded to support the amendment and invited them to the Executive Mansion. For instance, he had a long talk with Representative James S. Rollins of Missouri, who had voted against the amendment in June, and entreated him as an old Whig and follower of “that great statesman, Henry Clay,” to join him now in supporting the measure. When Rollins said that he was ready to vote for the amendment, Lincoln pressed him to use his influence with the other congressmen from his state. “The passage of this amendment will clinch the whole subject,” the President assured him: “it will bring the war, I have no doubt, rapidly to a close.”
If Lincoln used other means of persuading congressmen to vote for the Thirteenth Amendment, his actions were not recorded. Conclusions about the President’s role rested on gossip and later recollections like those of Thaddeus Stevens, who remarked, “The greatest measure of the nineteenth century was passed by corruption, aided and abetted by the purest man in America.” Lincoln was told that he might win some support from New Jersey Democrats if he could persuade Charles Sumner to drop a bill to regulate the Camden & Amboy Railroad, but he declined to intervene, not on grounds of priciple but because, he said, “I can do nothing with Mr. Sumner in these matters.” One New Jersey Democrat, well known as a lobbyist for the Camden & Amboy, who had voted against the amendment in July, did abstain in the final vote, but it cannot be proved that Lincoln influenced his change.
Whatever the President’s role, in the final ballotting more than two-thirds of the House members voted for the Thirteenth Amendment and submitted it to the states for ratification. Celebrating, the House adjourned after inadvertently sending the resolution to the President, who happily signed it on February 1. He was untroubled when senators pointed out that, according to a Supreme Court decision of 1798, presidential approval was not required for constitutional amendments. He was convinced that, with or without his signature, the Thirteenth Amendment would root out “the original disturbing cause” of the rebellion and would fully settle all questions about the legal validity of the Emancipation Proclamation. Finally the country had “a King’s cure for all the evils.”
Source: David Herbert Donald, Lincoln, pp. 553 – 554
Seems as clear as daylight to me. 😮