The unusual and unlikely become somewhat more likely in an election year like this one . . . . . . in which a close race and a prominent third candidate could bring out the quirks in the American electoral system:
* In any close race for the White House it is possible for a candidate to win the popular vote but lose in the Electoral College, if his support is concentrated in too few states. This has occurred three times in American history, most recently in 1888 when Benjamin Harrison beat Grover Cleveland with fewer popular votes.
* Any state that John Anderson wins raises the possibility that no candidate will get the 270 electoral votes needed to win. In such a case, the House of Representatives would elect the president. This is now considered extremely unlikely this year, but two past presidents, Thomas Jefferson in 1800 and John Quincy Adams in 1824, have been chosen by the House.
* Recent elections have also seen electors, delegates to the Electoral College, break faith more frequently by voting for someone else. There is no constitutional provision requiring allegiance from electors. This has happened once in each of the last three national elections, and only eight times altogether. The number involved, however, was insignificant in each case.
Despite hints by some observers that the size of the turnout Nov. 4 could be larger than generally expected, most expect the trend toward smaller turnouts, in relation to the number of eligible voters, to continue.
"There is nothing in this election to indicate a change in the pattern" of declining votership in recent elections, says one expert.
But in the some key states -- populous and undecided -- county clerks note heavier than usual traffic in absentee ballots. In New York State, election officials report that servicemen registered there have sent in about 36,000 ballots compared with 30,000 in 1976. Illinois and Texas also suspect an increase in turnout among absentee voters.
A Newsweek poll taken last week shows Carter leading Reagan among registered voters by several percentage points, but Reagan gains a slight edge among those considered likely to vote. Thus, turnout on election day could affect the outcome considerably.m
The sands have shifted quickly in popular support for the candidates, but without clear direction.
A Washington Post poll released Nov. 2 found that 30 percent of those polled had changed their minds since September, and nearly 10 percent had changed their minds since last Tuesday (Oct. 28). A majority of those who have switched allegiances since the debate now favor Reagan, although among those who have said the debate was a major factor in their decision, more now favor Carter.
This softness in voter support could indicate how vulnerable Tuesday's outcome is to late-breaking developments in the news.m
The campaign outfits are showering voters with negative TV and radio ads in the last few days before the election.
The Carter campaign is scoring Reagan and Anderson, while committees for Reagan are doing likewise to Carter.
Carter decries the television ads in the South by pro-Reagan committees -- aimed, he feels, at his religious integrity. The Anderson campaign decries commercials by the Carter team that imply Anderson voted against civil rights legislation in the 1960s. Anderson in fact voted for the legislation. Carter-Mondale spokesmen say the ads are based on procedural votes Anderson cast and on some statements he made around that time.
Carter's media man, Gerald Rafshoon, has also introduced ads showing Reagan making a statement to an audience in January concerning the proliferation of nuclear weapons. Reagan denied making the statement -- at least as Carter presented it -- in the presidential debate Oct. 28.
The blame, if Carter loses, lies with John Anderson, said Carter campaign chairman Robert Strauss last week: Anderson can only "hurt Jimmy Carter and throw the election to Ronald Reagan."
But Anderson's own optimism is unblanched by polls that assess his support at about 7 percent nationally. Campaigning in those areas where he runs strongest, the Northeast, Far West, and upper Midwest, he says: "I am not predicating my campaign on any other strategy than winning on the fourth of November. I believe in miracles."
He has a $3.1 million reimbursement coming from the Federal Elections Commission if he scores 5 percent or higher in the election.