Barack Obama said Monday his campaign never gave Canada back-channel assurances that his harsh words about the North American Free Trade Agreement were for political show -- despite the disclosure of a Canadian memo indicating otherwise.

According to the memo, Obama's senior economic adviser Austan Goolsbee told Canadian officials at a Feb. 8 meeting in Chicago that the debate over free trade in the primary campaign was "political positioning." Goolsbee said his comments were misinterpreted.

In Texas, Obama said: "Nobody reached out to the Canadians to try to assure them of anything."

Hillary Rodham Clinton said Obama's campaign gave the Canadians "the old wink-wink."


Here are some factors to watch for in today's race:

Clinton's survival: Will the results prod Clinton to end her effort? Should Obama sweep all four contests, her hopes will be extinguished. Should she carry Ohio and Texas, she will no doubt fight to the next big battle, on April 22 in Pennsylvania. Trickier would be a split decision, in which Clinton won Ohio, for example, but lost Texas. Because of the way Texas allocates delegates, it is possible that Clinton could win the popular vote but lose to Obama on delegates.

Early totals could be definitive: In many elections, the first precincts reporting vote totals do not mean much. But the first returns in Texas, where all polls close by 8 p.m. CST, may count a lot. That is because they will represent "early voting" from before Election Day, which could make up one-third of the turnout.

Allegiances: In Texas, Clinton wants the Hispanic constituency -- which could be 40 percent of the vote -- that has favored her to loom as large as possible. In Ohio, the key is how much women dominate the electorate.

For Obama, critical constituencies include young voters and blacks. He is counting on heavy turnout in university towns such as Austin, Texas, and Columbus, Ohio.