Her husband, the former president, was campaigning throughout the state for his wife before Tuesday's pivotal primaries in Texas and Ohio.
"If somebody is here and they are undecided or you are trying to reach somebody who is undecided, here's my best advice," Clinton told the cheering crowd. "Ask them to decide how they will judge the next president when the president's term is over, not how you feel today at a rally."
Clinton said the success of the country's next president will be measured by three things.
"If you want the person to be able to say yes we are better off, yes our kids have a brighter future, yes the world is coming together and not being torn apart, (then) you know who the best president would be: Hillary," Clinton said. "You say yes to her on Tuesday."
According to recent polls, Hillary Clinton is in a virtual dead heat in Texas with her rival for the Democratic presidential nomination, Barack Obama.
The former president spent Sunday on a campaign blitz of Texas, campaigning in College Station, Marshall, Wichita Falls, and Abilene. On Monday, he was to make stops in Corpus Christi, Edinburg, Brownsville, Laredo, Eagle Pass, Del Rio and El Paso.
Hillary Clinton was campaigning in Ohio Sunday but was scheduled to return to Texas on Monday, when she'll hold a televised town hall meeting in Austin.
In Houston, Bill Clinton urged the crowd to vote for his wife because she would provide affordable health care to all Americans, make college more affordable, work to make the country less dependent on oil and bring the troops home from Iraq.
The Houston rally was filled with mostly Hispanic supporters. Hillary Clinton's campaign has been targeting the state's large Hispanic population, where she has strong support.
Earlier in the day, Bill Clinton and daughter Chelsea attended an early morning service at Houston's Lakewood Church, which has the nation's largest congregation.
Hillary Clinton has lost 11 straight contests, and many strategists argue that she must win in Texas and Ohio on Tuesday to continue.
The Texas contest is a hybrid primary-caucus, where most of the 228 delegates at stake are awarded based on the primary vote and others by caucuses held later in the evening. Voters can participate in both.
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