(The Hill) Mike Noble 08/17/19 06:00 PM In 2018 Arizona got a taste of what it was like to be a battleground state. Never before in modern Senate campaigns had two candidates put up such an expensive and nasty fight. The U.S. Senate race in Arizona saw a Grand Canyon-size investment in Republican Martha McSally and eventual winner Democrat Kyrsten Sinema. In 2020 all signs point to investors digging deeper to support fighter pilot-turned-appointed U.S. Senator McSally and astronaut-turned-candidate Mark Kelly. Fifteen months away from Election Day polling and financial data point to a close match-up that could determine control of the next Senate. Kelly leads fundraising efforts so far propelled by his wife former Rep. Gabrielle Giffords (D-Ariz.). But McSally now with the power of incumbency is gaining ground. Money and candidates aside maybe the most important factor in Arizona will be the two presidential candidates who top the ticket. Tracking polls conducted by OH Predictive Insights (OHPI) show Joe Biden is the strongest Democrat in the field of nearly two dozen. Biden beats President Trump in our latest poll. No other top contender for the Democratic nod fares as well with the likes of Sen. Kamala Harris (D-Calif.) Sen. Bernie Sanders (I-Vt.) and South Bend Ind. Mayor Pete Buttigieg falling short in these surveys. In these early looks its clear a Democratic wave could materialize in Arizona with the former vice president at the top of the ticket. Other Democrats who could be painted with the socialist brush face greater obstacles. But have no doubt: The McSally-Kelly race will be among the closest-watched across the country.