I doubt that Kennedy/Jackson could win the election. Without LBJ, JFK is guaranteed to lose Texas. And a few other Southern states too, which will be more swayed by the unpledged elector movement. The probable results are either a Nixon victory or a deadlocked electoral college. The House is Democratic, but controlled by conservatives and Nixon has won more states - putting him in a better position to cut a deal with Byrd and become President in 1961.
IMO, a Kennedy-Jackson ticket would win (whether or not it would carry Washington state)--either in the Electoral College or in the House. The only area where the lack of LBJ would hurt the ticket would be in the South. But there are surprisingly few states in the South which Nixon lost
narrowly. He lost Texas by 2.0 points, SC by 2.48, and NC by 4.22. I doubt very much that Jackson (who, though fairly liberal on civil rights, was not considered as offensive to the South on that issue as, say, Humphrey--indeed, Jackson had joined LBJ and JFK in voting for the jury trial amendment to the 1957 bill and in that respect was more satisfactory to the South than Symington) would cost JFK NC. If JFK only loses TX and SC, he still has 271 electoral votes, more than enough to win. But let's say he also loses NC and also that the Democratic state committee in LA decided on backing unpledged electors, as it almost did in OTL--and the unpledged slate wins. Nixon, even with TX, NC, SC, and the faithless OK elector he lost in OTL, will still have only 266 electoral votes--three short of a majority. (Note that all this assumes that Nixon will still carry WA, which is doubtful.)
So the race goes into the House. The breakdown of the House delegations in the 87th Congress (1961-3) was as follows:
D: AL, AK, AR, CA, CT, DE, FL, GA, HI, ID, IL, KY, LA, MD, MA, MS, MO, NV, NM, NY, NC, OK, RI, SC, TN, TX, UT, VA, WV--29 delegations
R: IN, IA, KS, ME, MI, MN, NE, NH, NJ, ND, OH, PA, SD, VT, WA, WI, WY--17 delegations
Tied: AZ, CO, MT, OR--4 delegations
https://en.wikipedia.org/wiki/87th_United_States_Congress
I simply cannot see a Nixon victory coming out of this--unless you assume that not a few but almost all of the southern Democratic delegations (including the Upper South ones) will vote for Nixon. I find this extremely dubious. Nixon's civil rights record was arguably more liberal than JFK's (the jury trial amendment of the 1957 civil rights bill) and not all southern Democrats (not even all Deep South Democrats) were economic conservatives. Besides, if by some miracle Nixon could get eight southern delegations to vote for him, he would still only have half the delegations--not a majority! If there were a prolonged deadlock, Scoop Jackson as the VP chosen by the Senate would become acting president--what's the point of blocking JFK to get that?
(Yes, Nixon will have carried a majority of states. So what? Is Stewart Udall going to vote for Nixon because AZ did? Is Ross Bass of TN--who would later be the only southern rural congressman to vote for the civil rights act of 1964--going to vote against JFK because Nixon, very likely because of religion, carried the state? Conversely, Walter Judd of MN isn't going to vote for JFK just because Nixon lost MN...)
Besides, whoever won the presidential election, the Democrats would retain control of the House. Southerners would not want to put their seniority and committee chairmanships at the risk of an angry Democratic caucus. It's not so surprising that so few Democratic members of Congress supported Nixon--indeed, I am not aware of any who
openly did so. (Senator Harry Byrd of Virginia maintained his usual "golden silence" enabling Nixon to carry the state as Ike had done in 1952 and 1956.)
Could there be a deal with Byrd to get a few Byrd electors to go for Nixon and thus have him win without going into the House? The obstacles to this are enormous. Most obviously, Nixon could make no open deal without alienating a lot of Nixon supporters, possibly including Nixon electors; and how would a secret deal be enforced? And Nixon's civil rights record (his support for strengthening the 1957 bill, his agreement with Rocky on the "treaty of Fifth Avenue,"
https://en.wikipedia.org/wiki/Treaty_of_Fifth_Avenue etc.) would have to give Byrd supporters pause. (If you think I am exaggerating the degree of GOP resentment of an open Nixon-Byrd deal, as conservative and Republican newspaper as the
Chicago Tribune warned: 'Worse things can happen in this country than the presence of Sen. Kennedy in the White House. Much worse would be the presence in the White House of a man who would be under obligations to a band of political brigands intent upon depriving citizens of their rights." Quoted in Edmund F. Kallina, Jr.,
Courthouse over White House: Chicago and the Presidential Election of 1960, p. 132.)
