Texas' top-of-the-ballot races are foregone conclusions.  Former Massachusetts Gov. Mitt Romney will almost certainly win the state's 36 presidential electoral votes today and tea party-backed Republican Ted Cruz will complete a once seemingly impossible rise from virtual unknown ex-state solicitor general to the first Hispanic from Texas elected to the U.S. Senate, replacing the retiring Kay Bailey Hutchison.  Cruz's contest against underfunded, former Democratic state Rep. Paul Sadler was easy compared to his upset victory in the fierce Republican Senate primary, when he shocked Lt. Gov. David Dewhurst, the choice of Gov. Rick Perry and the mainstream GOP.   A Democrat has not captured statewide office here since 1994.  Many down-ballot contests are also shaping up to hold few surprises, with Republicans likely continuing to dominate traditionally conservative parts of the state and Democrats controlling areas where they've usually done well. In fact, of the 198 major races across the state, only 19 look to be competitive.  Even with Texas getting four new representatives in Congress thanks to adding 4.3 million residents between 2000 and 2010, Republicans are likely to take 23 seats Tuesday, one more than the 22 they won out of 32 possible seats two years ago.