WASHINGTON — Sarah Palin is fortifying her small staff of advisers, buying a house in Arizona — where associates have said she could base a national campaign — and reviving her schedule of public appearances. The moves are the most concrete signals yet that Ms. Palin, the former governor of Alaska, is seriously weighing a Republican presidential bid.

While it is by no means clear that she would be willing to give up her lucrative speaking career and her perch as an analyst on Fox News to face the scrutiny and combat that would come with her entrance into the race, she is being pressed by supporters for a decision and has acknowledged that time is running out.

Two people familiar with the details of the real estate transaction said that Ms. Palin and her husband, Todd, had bought a $1.7 million house in Scottsdale, Ariz. Like others interviewed for this article, they would speak only on the condition of anonymity so as not to anger the Palins, who have become especially protective of their privacy in the maelstrom that has followed them since 2008. The Arizona Republic reported over the weekend on speculation in Scottsdale that the Palins were the buyers of the house, reporting the purchase was through a shell company that hid their identity.

While Arizona would be a more convenient travel hub for a presidential campaign than Alaska, there are other reasons the Palins might want a house there. Their daughter Bristol recently bought a house in Maricopa, which is near Scottsdale.