vote was far and away the most common. Similar bills have been introduced in nearly every session of Congress, but in most cases they were never debated nor acted upon.

The most recent examples where a popular vote proposal nearly passed were in 1969 and 1975, according to a Congressional Research Service report.

After the 1968 presidential election, third-party candidate George Wallace won 46 electoral votes. This prompted enough concern about third parties that Rep. Emanuel Celler, D-N.Y., proposed a resolution abolishing the Electoral College in favor of a popular election, in which the winner would have to win at least 40 percent of the vote. The resolution passed the House by a 338-70 vote, but it was blocked by a filibuster in the Senate.

After the close 1976 election, Sen.Sudan has accused South Sudan of attacking its oil fields along the border between the countries.

A government statement, which described the offensive as "severe", came after South Sudan said it had been hit by more air strikes inside its territory.

South Sudan's military spokesman said there was also a ground incursion, which was repulsed.

Such clashes erupted two weeks ago, the most serious since South Sudan became independent in July last year.

The countries fought a long civil war before South Sudan seceded, taking most of the oil fields although it has to export the oil using pipelines through ports in Khartoum's territory.

In January, South Sudan, which depends on oil sales for 98% of its revenue, shut down all of its oil fields in a row over the fees Sudan demands